Will a pr chip at 2800+ beat out a chip that can go straight to 3200+ with
no known issues.

You are forgetting that PR ratings are not the same for Athlon64 vs XP.
An Athlon64 2800+ is probably about equal to a XP3200+ in 32bit. And you
can overclock Athlon64 just as easily as the XP on any of the newer boards.

Microsoft might make XP-64 a OEM product ONLY

Why would they do this?

rms