Well you need to tell us more information for anyone to help.
First are you going to use software, or hardware raid?
software raid you setup through your operating system.
hardware raid you setup through your motherboard or an add in card that typically fits in a pci slot.
if your doing software raid, which i presume you are, you need to tell us what operating system you are using. Depending on the OS it may be supported, unsupported, or unofficially supported.
When creating a software raid you need to consider that if your OS hard drive fails your still somewhat up a creek. You need to make sure the new OS you load will be able to recognize your software raid you created or your data will essentially be lost.
Hardware raid on the otherhand does not have this problem, but requires specialized hardware to work. Either through your motherboard or an add in card. The raid will work no matter what happens to your OS hard drive. But if the hardware raid device, (mobo or card) dies you need to replace it with an identical piece of hardware for your raid to function again. Some of the better raid card manufacturers do not have this problem.
Take the info i gave you into consideration when you post back.