Well, I decided to customize my XP, which I have never quite got round to doing.
SplitBrowser - Enables multiple Firefox windows to be run at once, and they can be places anywhere.
StumbleUpon - Suggests sites depending on what your interests are, works very well.
Zune - A very smooth Black and Orange theme for XP, straight from Microsoft.
AquaTint Black Gloss theme for Firefox.
GREASEMONKEY IS NEEDED FOR THE FOLLOWING!
RS Highs - Adds F2P and P2P combat level to the RuneScape highscores, very, very useful.
Black YouTube - A perfect script, makes YouTube much more attractive.
YouTube Lyrics - Displays the video lyrics right next to the video, making it easy to read along. Scans many sites. Also removes all ads on YouTube.
YouTube High Quality - Automatically plays videos in higher quality, and also makes downloading videos easy.