pretty much as everyone mentioned above.
If you wanna go x64 then vista is the way forward as the XP x64 was kinda a stepping stone and not many drivers are widely available.

I use Vista x64 myself at home and theres no problems with any drivers for me.

The main differences are 64 bit software programs / games should run smoother/quicker. With 99% of apps / games they will be x86 (32 bit) and there wont be any difference what so ever.

using a 64-bit computer and OS will just mean you can multi-task a whole lot better and have multiple programs running at the same time with no loss in performance.

XP64 still lacks alot of driver support.

If your going 64bit and want to fully utilise it in the OS, your best off with Vista tbh if you 'want' to run windows...

vista is either

XP 64 suffers lack of drivers, or it did but check with you hardware manufacturers same with Vista

32bit systems run out of addresses and so could only support upto 4gig of RAM, whereas 64bits allow many more registers and so support a lot more memory.

Can some explain, in fairly simple terms :0, the difference between 64 bit and 32 bit operating systems.

Are there any special requirements to install XP 64-bit?

Are there any compatibility issues?

Is Vista available in 32/64 bit or just one?

Thanking you.

xxx