Short answer: From the manufacturer's webpage.
I'd suggest not using RAID unless you know what you're doing, which (I do not wish to appear rude but...) you do not. RAID isn't a simple run-of-the mill thing. For instance, do you know what RAID level you wish to run? Do you know the drawbacks/advantages?
For instance, I run a RAID 0 setup. Though this allows for fast read/write speeds, if one drive fails, all the info is toast. You can other levels of RAID as well for redundancy of information, though this will cut your total storage room down.
Long Answer: You're probably using nForce by nVidia. Go to their webpage and look for it there. They have a tool that should be able to identify the hardware and present you with the best possible driver for it.
Good luck, though I'd suggest reading up first!
Ryeguy, January 2009
