Hooking up two HD's: two different types, two different OS's

I'm not sure if this is possible, but...

I have two hard drives that are important: one is my 500GB SATA drive running Windows XP Pro, that basically has everything I've done in the last three years on it. The other is a 80GB IDE drive that has Windows 7 Ultimate installed on it currently that doesn't have anything on it I can't bear to part with.

My question is, is there any way I can set up one of them as a secondary drive I can access through the other, just long enough to transfer the files dearest to me to the IDE drive so I can format the SATA (it's full of spyware and the like I can't seem to get rid of, and I want to upgrade it to Windows 7 as well), or is this something that just isn't possible?

This is not really a problem. You should be able to select which of the HDDs to boot first in the BIOS settings. If you mess thigns up, no data should be lost anyway, and you'd be fine as long as you reverted to your previous setup.

Alternatively you could just reinstall Win7 on the 500 GB HDD without formatting it. The new Win7 installation will rename the old windows installation windows.old, and not delete any files. I've done this a few times myself. Works wonders.

Mirage is correct, but a thought:

If you have your sata as a slave, couldn't you run anti-virus scans on your slave (sata) drive when you boot from the master (IDE)? Spyware issues can be solved by running your standard run-of-the-mill software, usually (I've never seen a spyware issue so bad you had to re-install)