Your OEM XP, is it a Lenovo branded one? I'm asking, because you said you bought it on ebay, and OEM's vary quite a lot! With some, you can actually just install the operating system, which is great, but with Lenovo OEM's, you'll have to go through the whole restore process. Someone please correct me, if I'm wrong, and if there is a way to "restore" ONLY the OS! That would be awesome!
In any case, I would definitely start from scratch, format your hard drive, and then do a fresh install from your XP disc(s?)!
How come you don't like Vista, if I may ask? It appears to me that you made the decision to ditch Vista in favor of XP very fast...?
Enjoy your new Thinkpad!

15-inch Core 2 Duo ThinkPad T60p | Ivy-Bridge (Late-2012) Mac mini w/ quad Core i7-3615QM 2.3GHz, 16GB DDR3-1600MHz RAM, 240GB+180GB Intel 520 Series SATA III SSD's, 5x3TB Drobo 5D