Things I like set up on my XP system(obviously not complete, but it will help me get set up at the new job tomorrow):

Turn off filterkeys:
http://www.ofzenandcomputing.com/zanswers/463

Useful windows scripting tool. allows you to process everything in a directory recursively:
http://www.dailycupoftech.com/2007/03/29/quickly-perform-a-function-on-several-files/

Install this good stuff:
7-zip: http://www.lifehacker.com/photogallery/LH%20Top%2010:%20Free%20Windows%20Downloads/1650986
Foxit Reader: http://www.lifehacker.com/photogallery/LH%20Top%2010:%20Free%20Windows%20Downloads/1650966
SyncBack: http://www.lifehacker.com/photogallery/LH%20Top%2010:%20Free%20Windows%20Downloads/1650910
Notepad++: http://www.lifehacker.com/photogallery/LH%20Top%2010:%20Free%20Windows%20Downloads/1650562
Textpad:
YIM:
Gtalk:
of course, FIREFOX!!!!: http://www.lifehacker.com/photogallery/LH%20Top%2010:%20Free%20Windows%20Downloads/1650166
VLC: http://www.videolan.org/vlc
K-lite Codec pack
Winamp: http://www.winamp.com/
Media Player Classic: http://sourceforge.net/projects/guliverkli/
John's Background Switcher:
gVim:
Putty/PSCP/PSFTP:
TightVNC: http://www.tightvnc.com/
CygWin: http://cygwin.com/
ImgBurn: http://www.imgburn.com/
GDS: http://desktop.google.com
PDFCreator: http://sourceforge.net/projects/pdfcreator/
XP PowerToys: http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx
IrfanView: http://www.irfanview.com/
Crap Cleaner: http://www.ccleaner.com/
Torpark: http://www.torrify.com
AVG:
DVD Decrypter:
DVD Shrink: http://www.dvdshrink.org/
DVDFabDecrypter:
Soulseek: http://www.slsknet.org/
Ad-aware: http://www.lavasoftusa.com/software/adaware/
Spybot S&D: http://www.safer-networking.org/en/index.html
md5sum:
Windows Defender: http://www.microsoft.com/downloads/details.aspx?FamilyID=435bfce7-da2b-4a6a-afa4-f7f14e605a0d&\1displaylang=en
mp3DirectCut: http://mpesch3.de1.cc/mp3dc.html
RealAlternative: http://www.free-codecs.com/download/Real_Alternative.htm
Exact Audio Copy: http://www.exactaudiocopy.de/eac.html
TClockEx: http://www.rcis.co.za/dale/tclockex/about.htm
Eraser: http://eraser.sourceforge.net
DBAN: http://dban.sourceforge.net
JDiskReport: http://www.jgoodies.com/freeware/jdiskreport/index.html
AutoHotKey: http://www.autohotkey.com/
CPU-Z: http://www.cpuid.com/cpuz.php
Ethereal:
memtest86:
contig: http://www.sysinternals.com/Utilities/Contig.html


Firefox Extensions:
Aging Tabs
AllPeers Beta
Download Sort
Download Statusbar
DownThemAll!
El Jay Icon Maker
FireFTP
Flashblock
Forecastfox
Greasemonkey
IE Tab
Stumbleupon
WebmailCompose


Greasemonkey Scripts:
Google Calendar Display Current Time




I want to check this stuff out:
Windows Powershell: http://www.microsoft.com/windowsserver2003/technologies/management/powershell/download.mspx
SysInternals Utilities: http://thepiratebay.org/search/sysinternals/0/0/0
GAIM
Miranda IM:
450 freeware solutions: http://www.econsultant.com/i-want-freeware-utilities/
WinMerge: http://winmerge.sourceforge.net/
Gmail Drive: http://www.viksoe.dk/code/gmail.htm
Heavyload: http://www.jam-software.com/freeware/index.shtml
Business Plan: http://www.planware.org/busplan.htm




It's not freeware, but essential for dual-monitor love:
Ultramon: