Using 64-bit without Vista? I know window XP uses 32-bit, and as I have read Vista's "fine print". I'm not going to buy it and support mircrosoft's privacy invitation. Does any other operating system support 64-bit? Or does Windows Xp have a mod?
Yeah, there's a really unique mod to XP called Windows XP Professional 64 bit Edition. That being said, there's nothing wrong with using Vista 64 unless you have a driver conflict.
XP 64-bit edition for x86_64 systems (not to be confused with Itanium Windows XP 64-bit), but I still hear there is a lack of drivers for stuff on that platform. However, I don't personally run it and have only installed it for some people.
Various Linux distributions, Solaris, and the *BSDs are also available in 64-bit, just to maximize your choices.