The Top 5 Game: Essential Software

So we were talking around the office about how all of our desk computers are completely shot to hell from years of software tests, installs/uninstalls, weird registry entries, and data fragmented up and down the block. Ok, my computer's in worse shape than most (they actually brought the beast down from SF for me, much to my dismay), but those of you who like to experiment on your own systems know how nice is it to stop the insanity and start over with a clean slate.

This brings me to today's Top 5 Game:
If you had to choose, what five programs do you consider must-installs on a fresh and clean OS?

Here are mine (XP):

1. AIM (but only when combined with AIMutation for tabbed browsing, etc)

2. iTunes

3. WinRAR

4. Firefox (extensions: IE View, BugMeNot, Firesomething, GoogleBar to start)

5. Spybot Search & Destroy

Ok, what are your faves?