39-pin to 15-pin connector

I am new to this so feel free to chuckle as I try to describe the problem. I have a raid set up on my machine with a removable second hard drive. (Western Digital 80 GB, 39-pin + four larger pins, plus two smaller pins for the fan, made in 2004). The raid casing has a tiny fan on the front which was becoming very noisy due to a worn out bearing, so I ordered a new fan. I thought I would like to upgrade so I also ordered a new 500 GB hard drive. (Seagate). Being naive enough to believe that all hard drives would have the same connectors, I did not even think to check. When it arrived I noticed that the new one has 15 “pins” and 7 pins (not pins really just parts of the card that stick out with little metal tabs) + four small pins.

To see pictures of these connections see this page: Untitled Document

Well, the connection from the hard drive to the raid drive casing is a 39-pin connector which goes to a little computer card attached (glued?) to the female connection that is attached to the casing and goes to the actual machine which has a 39 pin connector and a four pin (large) connector. Can I connect this new hard drive? Do I need to get a new connector for the raid casing? Do I need to change the actual connection inside the machine (from the raid casing to the machine)? How do I know what to buy and where can i buy it? These hard drives have been sitting on my desk for a month and I am stumped as to what to do with them. Are they paper weights? (Please say no)