Oh, one other thing. Reverting to XP will not be possible for people who need new hardware. Microsoft has already stopped, or will very soon stop, providing new XP licenses to the big computer manufacturers. So if you buy a new machine, chances are XP won't be available at all, no matter what kind of tantrum you throw.
You can get XP from the OEM's (Dell, etc.) until the end of the year. OEM's are not required to stop shipping units with XP until 2008. Stock up now!