I would go with the 64 bit. I have vista 32 bit and it looks like it's going to be a pain to bump up to 64 bit. The main reason I want to switch to a 64 bit is that the 32bit is only able to support 2gigs of ram for any one application, while a 64 …
I have Vista 32bit and for the most part my performance is pretty bad. Tortage-Night was at least playable, but as soon as I changed to day I just quit out of frustration.