Well, RAID-5 is more then just "add another drive" he'd have to have a controller, onboard or PCI, that would manage it. RAID-5 is something that works out slick for most cases, as you gain some nice features - you get 2/3 of the space vs. half, and your performance is fairly good read/write.
RAID-0 is fastest, read and write, no data safety.
RAID-1 is just as fast as RAID-0 on READ in most cases, but slower on WRITE. Data safety in that both drives are mirrors, so if one drive fails, you're OK.
RAID-5 is not as fast at read as either RAID-0 or RAID-1, but it's faster on write then RAID-1, and you don't lose as much space. RAID stays alive and kicking able to rebuild. Here's the hitch for Ron: he'd have to buy another drive, have a PSU that would support hanging another raptor, and he'd have to have controller level support for RAID-5; true on some MOBOs, not all, and the controller cards that do RAID-5 aren't nearly as cheap to get a decent one.
Up to you Ron, what is the end goal?
