Lots of good programs here.
To add a few that aren't yet listed:
CacheMan - Memory management program that I use once, save, and never again.
NBGCleanR - Registry cleaner that works and doesn't mess up your PC. You will be amazed at all the "junk" left behind and deleted by this.
ATM - Shows % of processor being used, and what programs are using it.
WinHTTrack Website Copier - Download entire websites for offline viewing. Very nice.
TrayPlay - Simple, but effective CD player for Windows. No frills, low resource.
Advanced MP3 Home Studio - Program I use to rip CDs to MP3 form.
EditPad Lite - Notepad, enhanced and with tabbed windows. Nice for text and HTML creation.
And lastly...
ESPN BottomLine - Great for sports fans that want news and updated scores without having to view a website. A sports ticker that sits above your taskbar and shows scores and news categorized by sport.