Still here ! Will you put that 2nd hard drive back in the old computer once you're done transferring data from it to your new PC, durkinjt? If so, maybe you shouldn't risk booting from it in the new PC, because that'll mess up the existing XP installation on there, which is set up for the old PC specifically. You must be 110% sure to boot from your newly insalled Windows XP, and not from the old drive in this case.

Unless it's a really large amount of data that you need to transfer, I would consider using other options for this, like USB storage or CD/DVD discs (or even a network cable between the two PC's, if you'd like to learn how to do this). Like Bob said, it's a big no-no to transfer your old Program Files from one Windows installation to another - you'll have to reinstall those programs from scratch on the new PC. The data you can transfer is usually stuff like My Documents, Internet browser favorites, E-mail client mailbox, and some other user settings.

If you don't need to put that hard disk back in the old PC (and consequently don't need to use the Windows install that's on there anymore), there's not much you can do wrong. Just connect it to SATA port 2, 3 or 4 (your new HDD should be on SATA1 as mentioned previously) and check for its presence in Disk Management, after booting into your new XP installation.