Thats the next project. Just wanted to test the hardware with a familiar OS first. I've got the Vista Ultimate x64 you mentioned ready to install later in the week
Another thought: I wonder how many people with 64bit cpus have actually tried a 64bit OS ?
I installed x64 XP a coupla years ago & had the lack of drivers problem you mentioned, eventually having to replace unsupported hardware with new bits.
Its definately a lot faster than 32 bit as I've always dual booted the 2 as I've a few old games that wont install on x64