... and hope for the best!
I've just done the same. However had to buy a new mobo/cpu/mem as nuked my other last week. So 2nd install.
It may not be what you expect, infact its kinda frustrating at first.
If you have an AGP rig like mine, you could be in for all sorts of fun - of the wrong kind!
NVidia are not releasing NForce3 Vista64 driver updates it seems, which is the absolute pits and shame on them. It may mean I have to trash this new mobo already, and it could FORCE me to upgrade to PCIe. Joke, just not a funny one.
My vid card is a very capable Gainward Bliss 7800 GS+ 512mb, I've installed the latest drivers from NVidia, but the graphix result in the Vista test has dropped from 5.9 under XP to 5.0 in Vista64.
Its also feeling sluggish as an O/S, even typing this, there is some type lag. CPU is now X2 6000+ 3ghz, got 4gb of PC-2 6400 too, in all its fairly high end other than those who would say AGP isnt....