RAID stands for redundant array of inexpensive disks. There are a few versions of RAID. RAID0 is striping, It basically splits the work of reading a file between 2 or 4 disks. RAID 1 is Mirroring. It's just for fault tolerance. RAID 5 is not recommened because there aren't cheap IDE RAID cards, and isn't fast. Now the benifit's. RAID 1 and 5, allmost none in home PC's. RAID 0 can be faster than certain applications, but there is the risk that if a drive fails, you lose the entire array. And really there isn't as big of a performance increase as people think there is. Really, unless you're doing video editing, a Single SCSI drive is a better option than IDE RAID0.