Easiest way to solve this:
1. Download the drivers for BOTH drives.
2. Go to Control Panel >> System >> Hardware Tab >> Device Manager
3. Select your first drive and uninstall it.
4. Select your second drive and uninstall it.
5. Shutdown
6. Check to ensure that one of your drives has its jumper settings as master and the second has its jumper to slave (if they're on the same IDE cable).
7. Unplug one of your drives. Keep the other plugged in.
8. Boot up, allow the drive to detect, install, and IF IT ASKS...use the drivers you downloaded. Otherwise, allow windows to install it. Don't install the drivers unless it asks.
9. Test the drive...make sure it works.
10. Shutdown the computer.
11. Plugin the second drive.
12. Repeat #8 and #9
13. Everything should be good after doing these steps. If not, it's possible that there is a bad drive or a BIOS setting getting in the way of things...you'll have to approach it from that direction if so.