And, incidentally, if the RAID supports ATA133 that means it is just IDE RAID. The way you phrased the question, it seems like you are a little confused about what RAID is. RAID means Redundant Array of Independent (or Inexpensive) Disks. Basically, it allows you to do several things. You can check out the AnandTech
FAQ on the different types of RAID array. IDE is a drive interface. You can have IDE, SCSI or SATA interfaces. You can have a RAID array using any of these interfaces. Your board supports IDE RAID with most likely the ability to do at least RAID 0, which allows you to use (ideally) 2 identical drives and create, what the system recognizes, as one hard drive. So, for example, if you RAID 0 two 60GB drives, the system will report a drive size of ~120GB. RAID 0 stripes your data across both drives to allow faster write times. In my experience the benefits are limited, unless the computer is a server dealing with large database files and the like. Check out the FAQs here, and Google around to find more info. Personally, I don't use RAID in a home setting as I don't find the benefits compelling.
\Dan