Intel has been kind in not changing they're Socket 775 in a number of generations. 99% of the Intel processors out there will use this socket. Don't be scered.

What advantage do you think you will achieve from a 64 bit OS? Aside from future proofing... MS has already addressed this with their Easy Upgrade, allowing any Vista user to upgrade their OS online, and for a small upgrade fee. I am disappointed with my Vista64, and am eagerly awaiting the day when all my applications have native 64bit support.