A hardware raid card that offloads all the raid features from the cpu. If your talking cheap raid on board - it's completely software typically. Unless we are talking about high end server boards.
The best is going to be VERY expensive, so you should list a price range and port number you are looking to buy, unless you will for sure only need 2 drives.
fakeraid might perform well enough for you?
SATA or IDE? I have an older 4 port IDE, if you need one shoot me a PM but I would assume you need SATA.