Frequency counts of system file extensions for Windows 7 machine

Powershell script to enumerate all system extensions from c:\windows

#get system file type counts
$sysdir= "C:\Windows"
$cntsfile= $env:USERPROFILE+"\Win7SystemFileExtsCnt.txt"

try{
Get-Childitem $sysdir -Recurse  -ErrorAction Ignore |
     WHERE { -NOT $_.PSIsContainer } | 
        Group Extension -NoElement | 
            Sort Count -Desc | Out-File $cntsfile
} catch {}

#get computers age as of last update
$OS = Get-WmiObject -Class Win32_OperatingSystem 
$InstalledDate = $OS.ConvertToDateTime($OS.InstallDate) 
$Span = [datetime]::Now - $InstalledDate
$age = New-Object DateTime -ArgumentList $Span.Ticks
Write "Computer's age is:  $($age.Year -1) Years $($age.Month -1) Months $($age.Day) days old" | Add-Content $cntsfile

Results of system extensions frequency counts (I added % after)

Ext Counts  %
=== ====== ======
.dll 30800 25.54%
.cat 19125 15.86% //(.cat) is packaged of an arbitrary collection of files
.mui 10994 9.12%  //Multilingual User Interface application resource files
.mum 8987 7.45%   //Windows update file 
.cdf-ms 6956 5.77%  //A CDF-MS file contains the compiled version of a .MANIFEST file
.exe 4316 3.58% 
.inf 3262 2.71%  //Setup Information file is a plain-text file
.ttf 3043 2.52%  
.GPD 2758 2.29% //GPD files are used for creating Unidrv minidrivers
.sys 1882 1.56%  
     1705 1.41%
.PNF 1340 1.11% //system-maintained configuration file that is created when an .INF file is run.
.xml 1268 1.05%
.man 1265 1.05% //short name for .manifest file
.aux 1262 1.05%
.mof 1224 1.02%
.png 1120 0.93%
.ini 1102 0.91%
.PPD 814 0.68%
.wav 793 0.66%
.tmp 693 0.57%
.nls 567 0.47%
.fon 560 0.46%
.txt 543 0.45%
.chm 474 0.39%
.ptxml 455 0.38%
.dmp 413 0.34%
.ps1 387 0.32%
.admx 378 0.31%
.adml 373 0.31%
.log 371 0.31%
.dat 363 0.30%
.xrm-ms 360 0.30%
.config 338 0.28%
.H1S 320 0.27%
.cur 312 0.26%
.nlp 311 0.26%
.tlb 309 0.26%
.otf 307 0.25%
.xsd 307 0.25%
.compiled 292 0.24%
.resx 270 0.22%
.rtf 267 0.22%
.cs 260 0.22%
.jpg 252 0.21%
.mfl 243 0.20%
.icc 200 0.17%
.msc 181 0.15%
.EXP 172 0.14%
.rat 168 0.14%
.bin 165 0.14%
.cpl 165 0.14%
.efi 164 0.14%
.gif 164 0.14%
.sql 162 0.13%
.ax 157 0.13%
.h 147 0.12%
.aspx 144 0.12%
.DXT 130 0.11%
.browser 124 0.10%
.icm 120 0.10%
.pf 116 0.10%
.OCX 115 0.10%
.psd1 113 0.09%
.rs 108 0.09%
.ps1xml 103 0.09%
.bmp 102 0.08%
.GDL 95 0.08%
.tbl 94 0.08%
.x32 94 0.08%
.pdb 92 0.08%
.htm 90 0.07%
.sdb 86 0.07%
.ico 82 0.07%
.ins 78 0.06%
.jtp 77 0.06%
.cab 76 0.06%
.emf 70 0.06%
.IMD 69 0.06%
.targets 69 0.06%
.mib 68 0.06%
.wmv 67 0.06%
.bcm 64 0.05%
.uce 64 0.05%
.xsl 64 0.05%
.iec 62 0.05%
.cfg 59 0.05%
.ime 58 0.05%
.JS 50 0.04%
.propdesc 49 0.04%
.vbs 47 0.04%
.ascx 44 0.04%
.default 44 0.04%
.rsp 42 0.03%
.vdf 42 0.03%
.web 42 0.03%
.CMB 40 0.03%
.html 40 0.03%
.ttc 38 0.03%
.css 37 0.03%
.stl 35 0.03%
.rom 34 0.03%
.cmdline 32 0.03%
.diagpkg 32 0.03%
.err 32 0.03%
.out 32 0.03%
.uninstall 32 0.03%
.com 31 0.03%
.theme 29 0.02%
.SCR 27 0.02%
.avi 25 0.02%
.acm 24 0.02%
.dtd 24 0.02%
.JSON 24 0.02%
.master 24 0.02%
.reg 24 0.02%
.tsp 24 0.02%
.etl 23 0.02%
.ccu 21 0.02%
.amx 20 0.02%
.vp 20 0.02%
.vrg 20 0.02%
. 18 0.01%
.hlp 18 0.01%
.lng 18 0.01%
.db 17 0.01%
.CompositeFont 16 0.01%
.dlm 16 0.01%
.H1K 16 0.01%
.ngr 16 0.01%
.rll 16 0.01%
.sep 16 0.01%
.prof 15 0.01%
.DIC 14 0.01%
.wmf 14 0.01%
.am 12 0.01%
.ani 12 0.01%
.comments 12 0.01%
.drv 12 0.01%
.inc 12 0.01%
.nlt 12 0.01%
.psm1 12 0.01%
.rpo 12 0.01%
.scp 12 0.01%
.cmd 11 0.01%
.NTF 11 0.01%
.crl 10 0.01%
.lex 10 0.01%
.olb 10 0.01%
.Tasks 10 0.01%
.wma 10 0.01%
.lnk 9 0.01%
.old 9 0.01%
.gmmp 8 0.01%
.job 8 0.01%
.lxa 8 0.01%
.mlp 8 0.01%
.rld 8 0.01%
.sdi 8 0.01%
.url 8 0.01%
.cmf 7 0.01%
.jnt 7 0.01%
.tmp-tmp 7 0.01%
.toc 7 0.01%
.Wdf 7 0.01%
.bat 6 0.00%
.cap 6 0.00%
.cch 6 0.00%
.cpx 6 0.00%
.ds 6 0.00%
.mid 6 0.00%
.mpg 6 0.00%
.res 6 0.00%
.shp 6 0.00%
.win32manifest 6 0.00%
.GRM 5 0.00%
.16385 4 0.00%
.camp 4 0.00%
.cdmp 4 0.00%
.CHS 4 0.00%
.CHT 4 0.00%
.cov 4 0.00%
.cpa 4 0.00%
.cty 4 0.00%
.cw 4 0.00%
.dcr 4 0.00%
.dir 4 0.00%
.dls 4 0.00%
.dun 4 0.00%
.dvd 4 0.00%
.dvr-ms 4 0.00%
.fe 4 0.00%
.frm 4 0.00%
.h1c 4 0.00%
.H1T 4 0.00%
.hex 4 0.00%
.iso 4 0.00%
.isp 4 0.00%
.jpn 4 0.00%
.jrs 4 0.00%
.kor 4 0.00%
.mllr 4 0.00%
.mp4 4 0.00%
.msi 4 0.00%
.obe 4 0.00%
.phn 4 0.00%
.prx 4 0.00%
.ps 4 0.00%
.psc1 4 0.00%
.psd 4 0.00%
.smp 4 0.00%
.tbr 4 0.00%
.THA 4 0.00%
.uni 4 0.00%
.vb 4 0.00%
.vs 4 0.00%
.wmz 4 0.00%
.wsc 4 0.00%
.wwd 4 0.00%
.xbap 4 0.00%
.xsx 4 0.00%
.csv 3 0.00%
.ebd 3 0.00%
.idx 3 0.00%
.mp3 3 0.00%
.ser 3 0.00%
.acl 2 0.00%
.blb 2 0.00%
.BPD 2 0.00%
.BUD 2 0.00%
.chk 2 0.00%
.clb 2 0.00%
.dcf 2 0.00%
.desklink 2 0.00%
.devicemetadata-ms 2 0.00%
.dnl 2 0.00%
.doc 2 0.00%
.dub 2 0.00%
.ecf 2 0.00%
.fl 2 0.00%
.fx 2 0.00%
.GRL 2 0.00%
.hit 2 0.00%
.hkf 2 0.00%
.HPI 2 0.00%
.hrd 2 0.00%
.hxx 2 0.00%
.ird 2 0.00%
.LOC 2 0.00%
.mapimail 2 0.00%
.msstyles 2 0.00%
.org 2 0.00%
.OverrideTasks 2 0.00%
.pb 2 0.00%
.pdf 2 0.00%
.prm 2 0.00%
.properties 2 0.00%
.props 2 0.00%
.qtp 2 0.00%
.qts 2 0.00%
.qtx 2 0.00%
.que 2 0.00%
.rrr 2 0.00%
.s3 2 0.00%
.stp 2 0.00%
.t4 2 0.00%
.uns 2 0.00%
.vch 2 0.00%
.XEX 2 0.00%
.xpi 2 0.00%
.xst 2 0.00%
0 2 0.00%
0.1 2 0.00%
0.10165524 2 0.00%
0.106033 2 0.00%
0.1079901 2 0.00%
0.1083426 2 0.00%
0.10917137 2 0.00%
0.11277624 2 0.00%
0.12913793 2 0.00%
0.1371903 2 0.00%
0.139199 2 0.00%
0.144727384 2 0.00%
0.1496361 2 0.00%
0.2061428 2 0.00%
0.2176416 2 0.00%
0.25691211 2 0.00%
0.27929935 2 0.00%
0.2799157 2 0.00%
0.29565683 2 0.00%
0.29599 2 0.00%
0.3285044 2 0.00%
0.3397998 2 0.00%
0.35809623 2 0.00%
0.3822664 2 0.00%
0.4026523 2 0.00%
0.4058614 2 0.00%
0.4181747 2 0.00%
0.42556121 2 0.00%
0.43410679 2 0.00%
0.449033 2 0.00%
0.45415385 2 0.00%
0.52254527 2 0.00%
0.5814079 2 0.00%
0.601773 2 0.00%
0.6051029 2 0.00%
0.6179558 2 0.00%
0.6812641 2 0.00%
0.7166873 2 0.00%
0.7263375 2 0.00%
0.7559434 2 0.00%
0.762213 2 0.00%
0.786571 2 0.00%
0.8922087 2 0.00%
0.89321288 2 0.00%
0.910531 2 0.00%
0.95783 2 0.00%
0.975474 2 0.00%
0.9903645 2 0.00%
.01cad04b30e6c1f8 1 0.00%
.01caf13786f95966 1 0.00%
.01cb07fce6f4def3 1 0.00%
.01cbc8bc3c502f9d 1 0.00%
.01cbde138c673079 1 0.00%
.01cbf98efc018851 1 0.00%
.01cc061e0207fe70 1 0.00%
.01cc061e7b4627fd 1 0.00%
.01cc10096d9577dd 1 0.00%
.01cc1009cd04e555 1 0.00%
.01cc2cafb47f7f25 1 0.00%
.01cc366609526398 1 0.00%
.01cc43435e83bc45 1 0.00%
.01cc4343b4f5c6a7 1 0.00%
.01cc43a8ef1e5f83 1 0.00%
.01cc43af693564d0 1 0.00%
.01cc43afb503df66 1 0.00%
.01cc43b8b32a8a54 1 0.00%
.01cc43b90803edd2 1 0.00%
.01cc4400c9ea5a90 1 0.00%
.01cc440419f25b98 1 0.00%
.01cc449c6ea0256c 1 0.00%
.01cc44a2be60cbf0 1 0.00%
.01cc44c572f49e8d 1 0.00%
.01cc4542bdca9e7c 1 0.00%
.01cc454af005b30c 1 0.00%
.01cc454b3545c85c 1 0.00%
.01cc460965267b1b 1 0.00%
.01cc46143d5c1503 1 0.00%
.01cc4614a91661e6 1 0.00%
.01cc46d8c40504e4 1 0.00%
.01cc46df33556595 1 0.00%
.01cc46dfa5b64a8d 1 0.00%
.01cc47aaf31a8b9e 1 0.00%
.01cc487230e7398e 1 0.00%
.01cc4ad0b8666299 1 0.00%
.01cc4b9497b5ea61 1 0.00%
.01cc4c644032dc07 1 0.00%
.01cc4d2edee8ed9e 1 0.00%
.01cc4d4c95948401 1 0.00%
.01cc4df8a29b8a69 1 0.00%
.01cc4f97e9963f11 1 0.00%
.01cc505c148fcf9a 1 0.00%
.01cc5106d19d44e0 1 0.00%
.01cc5117dbacd143 1 0.00%
.01cc5118446ffb80 1 0.00%
.01cc51228d186b38 1 0.00%
.01cc5761a1913c7f 1 0.00%
.01cc88f886d56bf3 1 0.00%
.01cc9f3c273aed31 1 0.00%
.01ccbb437a7d323d 1 0.00%
.01ccd069f917befe 1 0.00%
.01ccdb7938594e57 1 0.00%
.01ccecb73fd30c50 1 0.00%
.01ccfe10bf065228 1 0.00%
.17514 1 0.00%
.ADM 1 0.00%
.APL 1 0.00%
.asp 1 0.00%
.bak 1 0.00%
.bcf 1 0.00%
.chr 1 0.00%
.CON 1 0.00%
.crmlog 1 0.00%
.CRT 1 0.00%
.CSD 1 0.00%
.Deployment 1 0.00%
.edb 1 0.00%
.ev1 1 0.00%
.ev2 1 0.00%
.ev3 1 0.00%
.EVM 1 0.00%
.fxh 1 0.00%
.gs 1 0.00%
.hhc 1 0.00%
.hhk 1 0.00%
.hve 1 0.00%
.lic 1 0.00%
.LTS 1 0.00%
.mif 1 0.00%
.mni 1 0.00%
.MPP 1 0.00%
.MST 1 0.00%
.mzz 1 0.00%
.policy 1 0.00%
.PPTX 1 0.00%
.PUB 1 0.00%
.sam 1 0.00%
.security 1 0.00%
.ses 1 0.00%
.SHD 1 0.00%
.soundpack 1 0.00%
.SPL 1 0.00%
.tif 1 0.00%
.trx 1 0.00%
.tsi 1 0.00%
.TTS 1 0.00%
.txt44A40B10-65CC-094C... 1 0.00%
.UDT 1 0.00%
.UNT 1 0.00%
.WIH 1 0.00%
.WIM 1 0.00%
.wsf 1 0.00%
.wtv 1 0.00%
.XLSX 1 0.00%
.ZFSendToTarget 1 0.00%
0.001 1 0.00%
0.002 1 0.00%
0.003 1 0.00%
0.004 1 0.00%
0.005 1 0.00%
0.10461536 1 0.00%
0.10533967 1 0.00%
0.1292296 1 0.00%
0.13285 1 0.00%
0.13718556 1 0.00%
0.1405288 1 0.00%
0.14254232 1 0.00%
0.14254263 1 0.00%
0.167389 1 0.00%
0.174178735 1 0.00%
0.17803239 1 0.00%
0.17803255 1 0.00%
0.19404605 1 0.00%
0.2 1 0.00%
0.2046951 1 0.00%
0.2046967 1 0.00%
0.2227912 1 0.00%
0.22733011 1 0.00%
0.23230623 1 0.00%
0.26146625 1 0.00%
0.26146641 1 0.00%
0.28082519 1 0.00%
0.28082551 1 0.00%
0.28379967 1 0.00%
0.28379998 1 0.00%
0.298835 1 0.00%
0.3 1 0.00%
0.30507196 1 0.00%
0.30507212 1 0.00%
0.3099874 1 0.00%
0.3323866 1 0.00%
0.3549553 1 0.00%
0.3609051 1 0.00%
0.36226255 1 0.00%
0.36226583 1 0.00%
0.37110625 1 0.00%
0.38856432 1 0.00%
0.38856448 1 0.00%
0.39093569 1 0.00%
0.391765 1 0.00%
0.4 1 0.00%
0.4183291 1 0.00%
0.437894 1 0.00%
0.47845 1 0.00%
0.47876 1 0.00%
0.48844412 1 0.00%
0.50275971 1 0.00%
0.5114928 1 0.00%
0.52039609 1 0.00%
0.52884151 1 0.00%
0.52884198 1 0.00%
0.55739516 1 0.00%
0.5624569 1 0.00%
0.56799012 1 0.00%
0.58400705 1 0.00%
0.58400752 1 0.00%
0.637903 1 0.00%
0.654845 1 0.00%
0.68749 1 0.00%
0.7006 1 0.00%
0.771799 1 0.00%
0.77724986 1 0.00%
0.783764 1 0.00%
0.80246 1 0.00%
0.85348 1 0.00%
0.85769 1 0.00%
0.8586653 1 0.00%
0.8586669 1 0.00%
0.87563 1 0.00%
0.90917 1 0.00%
0.916817 1 0.00%
0.93912 1 0.00%
0.9757269 1 0.00%
   120572 100%

Computer's age is:  7 Years 8 Months 17 days old

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