I set up the old config - without the new 1TB drive, and with both the XP and win7 drive and it all works -
Why is the Windows 7 drive needing the Win XP drive to work?
sounds like when you installed win.7 it sared the info between HDD's needing both HDD's for windows to boot. I'd say fresh install with only the OS intended HDD connected. Not even close to the most knowladgable on this site, but a good place to start since you have no info. on your new HDD yet. Good Luck!!
For those who meet similar problems and have no Recovery disk. BootSuite is another awesome option to choose.