Actually.... when you have multiple drives set up in a master/slave on the same cable, if the cable dies it will cause issues with both drive. You'd be surprised how many times I've fixed HD issues like this by simply swapping the cable with a new one. Thing is, if you replace the drive(s) you generally end up using the new cables that come with it, so if it was the cable, you'll never even know if your old drive still functions.
If it is indeed a controller problem, which it rarely is, then you have the choice of buying an expansion slot PCI controller (in this case I'd say go with a SATA one instead) or replacing the motherboard completely, which can usually be the most expensive of the choices cause you can almost never *just* replace a motherboard.