FYI
Vista home basic and Vista home premium are delivered only in a 32 bit version but a 64 bit version is available at minimum charge after you have bought the 32 bit version. Vista ultimate comes with both 32 and 64 versions on separate DVD's in the box.
As yet some divers are not yet available (graphic drivers are suspect). Most support software (including most anti virus programs) is in test and not yet fully released.
My advise would be to wait a few months before getting it and if you can afford it buy the ultimate version (for all the extras).