Is the "old cable" the one that came with your empeg? If so, it should be plenty long. The Eutronix cable (worth buying) is longer between the first drive and the IDE header on the main board. It gives more room between the drives and the board but will have no effect on the slack between the two drives.

Are you sure you're hooking it up right? The "folded" part of the cable goes between the two drives and the straight, unfolded part goes to the IDE header.