If you have a 40 pin HDD cable (black ends), then put the long end into the motherboard, the Maxtor (set to Master) in the middle plug, and the WD (set to Slave) in the end plug.
If you have an 80 pin HDD cable (blue on one end), that goes to the motherboard, and both drives should be set to CS (Cable Select). In this installation, the Maxtor should be on the end plug and the WD on the middle plug.
When booting, go into CMOS and confirm that both the Master and Slave on the Primary IDE channel are set to Automatic.