Benefits ? I guess the main one is DX 10 if you wanna play the latest games (none are out as yet tho) Also Vista does have a few tricks that will speed up performance over XP, esp if you have lots of RAM and multiple cores. Besides that, when they get around to fixing Vista 64, then that will also become a benefit.

Personally I wouldn't suggest changing to it as yet. Wait till they are up to SP1 or SP2 and Vista 64 has been worked on. I would say, probably an year.

You can read more about all this here:

http://www.anandtech.com/systems/showdoc.aspx?i=2917