First of all, I would like to state that I have a RAID capable mobo (Abit KT7A-R).
IDE RAID, especially in 0, 1, or 0+1 configuration, inherently has a few problems. IDE controllers can only write to one drive on a channel at a time. In addition, many motherboard-native RAID controllers, when putting 2 drives in RAID 0, fill one drive first and then the other, making it not a true hardware RAID. SO that basically nixes the benefits of IDE Raid.
An ideal RAID controller utilizes RAID 5 - if I am correct, this uses 3 drives, loses the capacity of 1 drive, and allows any drive to be rebuilt from the other two in case of failure. In my opinion, this is the most efficient and only worthwhile use of RAID. Most mobo-native RAID controllers cannot do RAID 5.
If you're serious about wanting to use RAID to get a fast and reliable array, you need to go SCSI raid in RAID 5. Yes, I have a RAID mobo- but I only got it because I wanted the ability to run an extra 4 IDE devices without buying a seperate controller. At any rate...... that's my spin on the subject.
SickBoy