Thanks to all of you for your responses. I have removed the hardware address jumper on the WD drive, as suggested, and connected the drive to the primary connector on the IDE cable. I still cannot "see" the drive in "My Compter", even though it shows up in Device Manager and on the BIOS and boot-up screens. When I right-click on "My Computer" and select "Manage", I can also see the drive, identified as disk 0, showing the correct size, and with the name it has on the old computer "Drive_C". I am unable to rename the drive, which I would think would make it visible if I gave it an unused drive letter. Any ideas on how to proceed from here?
By the way, the system continues to boot properly, so I don't believe there are any conflicts resulting from having 2 drives installed anmed "Drive_C".