there are some trial on the internet. I've heard it has lots of bugs. I would recommend to download the Windows Server 2003 64bit edition wich has been officially released about a year ago.
Ya but there is a XP profesional/home 64 BIT edition, it does have alot of bugs but my buddy said it takes advantage of the 64 bit architecture and is extreamly fast
the windows 64 bit is still buggy. they were wupposed to release it with their new file system, WinFS, but they decided to use ntfs still, so they could release it earlier with less bugs, lol