Some of you have PC133 that will NOT run at the same setting. You just have to get in there and try some things out. But if you do hose something, it is NOT our fault. Basically what you are doing is taking a bunch of little drives and making a big one. No not really, but close.
RAID comes in several flavors as well.
You have RAID 0, RAID 1, and RAID 5. Maybe even others, I don't really know. Let's say you need the alphabet displayed on your screen and it takes your current HD 26 seconds to pull the data off and get it to your screen. Now we can pull the alphabet data off the HD and get it to your screen in 13 seconds. RAID 1, or mirroring is much simpler.