From what I've read, the only version of Vista for a home user to get would be Vista Home Premium. I bought the OEM version of Vista Premium at Newegg last week for 119.00. A pretty fair deal I think.
As for 64 vs. 32 bit versions, I went with the 64 bit version because the CPU I bought was 64 bit.
So far the applications I have tried to run work fine in Vista. I use Second Life a pretty good bit. They claim not to support Vista, however it works just fine.
When I installed Vista, it had drivers for everything except for my Edimax wireless-G PCI card. The disk that came with the PCI card had driver on it for Win 98, 2000, and XP. I used the XP driver and it works fine.
Maybe it is on a case by case basis, but I have been fortunate with Win XP drivers, apps, and games running on Vista without a hitch.