ive been having problems with XP Pro x64 and just recently ive been having problems creating a stable XP 64 unattended cd, when i go into manage my computer local users and group always has a red X over it and when i go to defrag something using diskeeper it will stop after about 30 seconds and says that it cant continue because a snapshot of the drive is being taken (by idk what

) i know that XP 64 is built off of 2003 server, but which is better (stability/compatibility wise)? ive heard people say that development of XP 64 was pretty much halted half way so more people could work on Vista.
so i ask you, whats your choice of 64 bit OSes?