SATA gets off of the IDE standard which is based on the parallel protocol. SATA is Serial and has better potential at faster transfer rates.
There are two common forms of RAID on "normal" motherboards.
RAID 0 = two drives that are the same connected by two different cables. This allows the computer to read and write the data across both drives at the same time. i.e. 2 x 70 GB = 140 GB RAID system, called "Striping".
RAID 1 = two drives that are the same connected by two different cables (same as above). But on this one the computer writes the same data to both of the drives at the same time. This is best if you absolutely require no down time. If the first fails in any fashion, you turn off the computer plug the cable from the first into the second and turn RAID 1 off and you are up and going as through nothing happen. You would have to replace the bad drive and run the RAID 1 tool to get your system back to running a RAID 1 system. i.e. 2 x 70 GB = 70 GB (plus one back up) called "Mirroring".
There is also RAID 0+1 = equals both of these options put together, but requires 4 RAID drive hook-ups, that are NOT part of the "normal" RAID motherboard. Plus a couple of other RAIDs that are found on server motherboard and RAID controller cards.
Bottom line RAID = $$$$...
Soyo Dragon Ultra Platinum Edition powered by a P4 3.06GHz w/HT @ 533FSB
ATI Radeon X800Pro 256DDR <---Yeah!!! I finally got it!!!
1024MB PC3200, Creative Audigy LS, 2 x 40GB = 80GB RAID 0
Windows XP Pro, DOOM 3, CS, UT2004, BF1942 RtoR, CNC Generals
Finished Half-Life 2!!!!!!!!!!