Raid edition drives vs standard drives

How significant is the performance difference between say the WD Caviar Black and the RE3 series? Im in need of a high speed, high reliability storage solution for a server that suffered some data corruption this morning. As it is primarily a web server it doesnt need a ton of space, even 320 is far more than it really needs. Im curious if the RE drives are worth their price premium, if they are more reliable then its definitely worth it. I have never looked for drives for a raid setup before so i need help on this one.