Yeah, one will be the master and one will be the slave, with the top (black) plug for the master the lower (gray) plug for the slave and the blue plug for the motherboard. There are jumpers on the backs of IDE drives which you have to set to "master", "slave" or "cable select". If you set both drives to "cable select", master and slave will be determined by what plug they're plugged into, so I usually just use the "cable select" setting for both drives.
Glad to hear that you figured out your problem.
