Secret to XP is getting a good clean install, then turning off a lot of garbage.
Take the time to install only what you need, clean up the start menu.
Get the processes down in the 18 - 22 range. Turn off automatic updates.
In fact I don't let ANY software on my machines autoupdate.
Example, don't install the full ATI/Nvidia desktop utilities for your video card. Just the drivers.
Do that with everything. For flying AH you don't need a full AV suite, just Threatfire.
Vista is 16x worse
Windows 7 is vista repackaged with no real help on the BS.
I was a Win98SE fan for a long time, but XP isn't so bad if you keep it caged.
Keep it clean, and make sure it understands who the boss is. And the answer isn't Bill Gates