AND THE WINNER IS....

Archeon, with:

Your new harddisk probably needs an 80 pin IDE cable to function properly.

All I needed to do was to install the 80-conductor cable that came with the drive and all is well. However....

Also with an 80pin cable, it's necessary to put the master device on the end of the cable and the slave device in the middle. This wasn't so the case with 40 pin cable.

This didn't seem to be necessary. My IDE disk master is in the middle and the DVD is on the end. Seems fine to me now.