Stereodude
Not really a
I'm aware of that and didn't mean to give the impression that it could boot. I was simply speculating that the 3TB WD drive could be used under Win XP x64 without any issues despite it being unsupported by WD.Yes, Win XP x64 does support GPT, but for data drives only. It can't boot from GPT drives.
http://www.microsoft.com/whdc/device/storage/gpt_faq.mspx