dallastech

I have the same problem...i can't get my old Dell Dimension 4500 POS to recognize my 2nd harddrive that I am trying to add. I've tried various combinations of setting the jumpers on the main drive to master, cable select and the 2nd harddrive to the coresponding slave or cable select, but for some reason the 2nd drive keeps screwing it up.
What i mean is, it boots fine with the main drive on the end (black) connector of the IDE cable and set to master or cable select, but when i hook up the 2nd drive on the middle (gray) connector and set it to slave or cable select, it only shows the blue Dell logo and then says "insert a valid boot device" or something of the like. I try going to BIOS, but under the IDE configuration it has the master and slave grayed out as if it doesn't recognize either of the drives.
This is very frustrating, especially since it will boot up fine w/ just the main drive.
Any of you have any ideas? Should I switch the drives (main to middle and 2nd to end)? Could my 2nd drive be bad?