I've gotten the last parts for a hefty upgrade and i'm debating what OS's to install. I have an MSDN subscrition so i have full choice of OS's.

The new system is a Core2Duo, so i get 64 bit support, having been accustomed to and only dealing with 32 bit OS's, I'm not sure what relevancy i'm seeing if i move to the 64 bit bandwagon. I'm currently leaning towards an XP/Vista dual boot for application compatibility issues with vista in general, but i'm not 100% on that path.

What opinions do you have to offer regarding choice of OS's?

Specs:
E6600
2 gigs ram
Raptor HDD
Geforce 8800GS (320 meg)