I wonder what Charcit is trying to do.
I suppose that if he (she/it) was trying to use an upgrade license on XP X64 (which has no SP3 available), he would have mentioned the fact. The upgrade will apparently not recognize XP 64 SP2 as qualifying for the use of an upgrade license. It looks like an error that Microsoft has never bothered to fix. (Probably because XP X64 was not easily available on the street. Very few upgraders out there. Corporate IT departments usually don't do upgrades, but rather fresh installs using customized images of the OS.)
As no upgrade-in-place is supported from XP to Win8, it would make sense to use a System Builder license. Then it won't matter what OS is in place. The System Builder license is actually less expensive than an Upgrade license at the moment.
If Charcit already has an upgrade license in hand from some source, and has XP X64, or can't install SP3 on a 32 bit version for some reason, I can only offer my sympathies, and hope that the price of a System Builder copy isn't too painful.
Given the amount of information in Charcit's post, I'd guess that he needs more help than a $100-$140 copy of WIn8.