I have just installed Windows xp 64 full version without failer

yey ! I happy!
I have few questions:
1)when ati drvier for windows 64 will be out? or does NGO DRIVER it for 64 too?
2)I have press "steam" to run after instaling Windows 64 and wihtout INSTALL IT , and it work.. if i would have install it regualr.. would it work? because some programs doesn't work under this windows
3)ok now it will be little "warez" but My mcafee 2005 doesn't work for this windows

is there any1 who can tell me what good antivirus can suppost this windows?
thanks
