Hi Kyle,
The only one supported "out-of-the-box" with SME 5.5 is a 3ware card, I think. With all the others, including Promise cards, Adaptec (which are Highpoint chip based), etc. require a dirver disk. There is a short guide on how to produce a driver disk for the Highpoint 370A based cards (search the forums for Highpoint). Charlie Brady has a driver for the Adaptec 2400A.
OS Independent RAID subsystems are available (eg. Accusys 7500A - RAID 1). These are self contained RAID subsystems that only require you to plug one IDE cable to the IDE connector of your motherboard. The RAID subsystem will appear as a single hard disk to your OS. RAID-1 subsystems of this type are fine and I have used them extensively. RAID-5 versions are available as well but suffers a performance penalty because the entire subsystem only communicates with the motherboard via one IDE cable. A card based RAID-5 controller usually has multiple channels and this increases the ability to transfer more data quickly.
Kelvin