Some words should be said on RAID: It is not always wise to use it, as it *may* - but not necesserily must - cause more trouble for the home user than it is worth it. Think of the situation you always have in mind, i.e. the most common reason, why most people want RAID: it is the mirroring to defend data when one harddrive goes down. But when you are not sure which of your two HDs is broken, you can lose your data by picking the wrong one for replacement. It may sound trivial, but is often not, when you use two identical drives for mirroring.
Another point goes to checking the drive status: How do you know when one of your drives is broken? Would you do regular checking from time to time or in everyday use? You would not want to go the first drive down and lose the second shortly after, because of perfect mirroring you did not even see there was an error!
These hints are not my personal opinion, but were mentioned in an article from a german computer magazine, which is quite popular in the technical oriented scene. I found them quite considerable when my brother-in-law asked me to build up a NAS. So I'm not argueing against RAID in general, but there are moments to be observed.
Good luck!