|Tubesandwires' response is on the money.|
But, do you know if your mobo already has SATA connectors? Do you already have the hard drives and are they PATA or are you planning to purchase another drive(s)?
If you are planning to get another drive and your mobo already supports SATA, you could just get a SATA drive. Or if you already have PATA drives and you do have SATA support on your mobo, you can get a SATA to PATA converter. But, unless it is a lot cheaper to do that I would go with the PCI IDE controller card because of the additional flexibility it provides.
One thing to note. When using a PCI controller card you will experience longer boots. I've used about three different PCI controller cards in different systems and I'd say the boots too anywhere from 45 - 60 seconds longer. But, that could just be my experience.