My List of Essential Windows Software

Mozilla Firefox - web browser
Mozilla Thunderbird - email client (minimize to tray is a handy extension)
CRT/SecureCRT Telnet/SSH - A much better telnet app then the standard windows one
SecureFX - A versatile FTP/Secure FTP app
mIRC - the defacto standard windows IRC client
Winzip
WinRAR
Trillian - A handy program to keep track of and chat with friends on the net
Quicktime - all the multimedia extentions to the Mac for use on PC
iTunes - its not the greatest, but it does everything good enough and all in one package
Winamp - for all your MP3 needs, still my favorite
Foxit Reader - a lighweight viewer for PDF files
LView Pro - a good image viewer/manipulator, the newer versions seem to suck, i use a really old version, 1.3
XnView - simple multimedia browser
Media Player Classic - a simple lightweight but feature packed media player
DivX - The popular MPEG 4 like audio/video codec
Xvid - open source codec
DVD Profiler - great tool for cataloging DVD collections
EAC - Exact Audio Copy - a flexible tool to rip CDs
Wireshark - A free ethernet packet sniffer for many platforms (formally Ethereal)
MIB Browser - basic SNMP MIB browser
IsoBuster - View/Extract info from CD image files
Daemon Tools - virtual cd rom emulator
Motherboard Monitor (MBM) - A utility to view all those fancy sensors on modern motherboards
TextPad
SecureW2 - EAP-TTLS Client (Wireless Security)
NTP - a Windows version of NTP to keep clocks synced
Ghostscript/GSView - a viewer for PS/postscript and PDF files, can also print PS files to non PS printers using standard windows printer drivers
Free Agent - An excellent NNTP client
Girder - PC remote control
Dscaler - PC TV viewing application
AVIcodec - Identifies codecs used in AVI files