This thread is funny. Five and a half years ago we had the same discussions here at Talkgraphics about XP; "No, I pass, I doesn't have anything I really need".
My web sites statistics now tell me that 83,5% use XP, 3,2% use Windows 2000, yet there is very little hard- or software that doesn't run on Windows 2000.
I strongly believe when we meet again after 12 months that the majority will be using Vista. I've seen every Windows version passing by in my life and it was always the same story. :D