I think your problem is due more because of the switch from Win 98 to XP than the version of UFT. It sounds like you downloaded the UFT patch. I think you need the foxpro/microsoft patch. Look again at that site:
Anyone with pre-3.0 versions, who has Windows XP and can't run UFT OR for ANYONE with version 3.0 or later, still having a problem with XP and can't run UFT... update the foxw2600.esl file from Microsoft.