Dell laptop doesn't like my "second" hard drive

I am fortunate to have "work" provide me with a laptop. I use it as delivered, while working, but I bought an extra hard drive (running XP) for it for my own use, just interchanging the drives.

All was fine with my Compaq Armada, but it was recently replaced with a Dell Latitude D610. I purchased a new caddy, installed the drive and swapped it out. Now I just get the little blinking light in the upper left corner. I ran the diag and it failed with the "Dell diagnostic partition not found" (paraphrasing).

Anyone know how to remedy this?