On my computer I have:
Linux-KDE as my main OS
I run xp in a popup window in my 4th desktop window in KDE (confused yet? heheheh).
I'm installing my third OS on my 12g drive & it'll be windows '98 so I can play my older games & it runs better on fat32.

Rob computer has Linux-KDE as his main OS & also runs XP in a popup window.

Tom has Linux-KDE as his main OS & has XP as his second OS. He also runs xp on his desktop, but he'll be putting Linux back onto it soon.

Rob's mom runs xp only

Rob's dad runs XP only as well.