before you add a pci ide card, you might want to check out your motherboard specs on the website of the company that manufactured it.
if you bought a Dell, or another pre-manufactured computer, and it is a fairly recent model, you may have an undocumented SATA connector and controller on your motherboard.
I have a Dell 4800, and it has just such a setup. i have both ide channels fully populated, but i could addd more hard drives via SATA.
you might have the same situation.