Question : Problem: Suitable SATA controller card

I have a Asus motherboard with available PCI slots.  I have a 150GB WD Raptor drive on SATA port 0 that carries the operating system.  I have a hardware mirrored pair of 160 GB Seagate drives on SATA ports 1 and 2.  The RAID 1 pair are set up using the Intel Matrix Storage Manager and the 82801FR SATA RAID controller.  All drives are operating with no alerts in the device manager.

I would like to add an additional WD Raptor SATA drive to the system.

I need advice regarding the selection of a suitable SATA controller card to carry additional SATA drives.

Answer : Problem: Suitable SATA controller card

Isn't it that the MB has four sata connectors?
Why You insist on buying new controller?

But anyway, as long as You will not use it as server, You can buy any cheap pci or better pci-e x1 card. Just follow the rule, and don't connect more than 2 drives to one controller.