It is possible that XP in the new environment has some conflict with this hardware, I assume there are differences in the hardware... Safe Boot might get past enough to allow it to come up, then you can see what is going on.
I am running the asus m4a89gtd pro motherboard with the AMD phenom II. I just got all new parts except for the hard drives for my setup. Upon boot it will load untill it shows the windows logo then reboots. I have 5 drives, 2 raided (just removed the raid card and 2 drives and transferred them to my new system.) and 3 independent drives. all drives are recognized and i can select from the boot screen witch i want to boot from. one of my drives has unbuntu and is loading correctly. The drive with Windows xp i know work because i just took it out of my last system and put it in to the new setup. when the grub loads it shows the drive in question on on / dev/ sdat1. i moved the drive to sata 1 port and still nothing?? Any ideas?