I've been trying to find a good article that talks about raid. Let me know if you find some good info on that.
Both Anand and Tom's Hardware have some good info on Heat sinks and fans. If you are not going to overclock you don't have to be concerned about going dual fan. Another consideration is noise. All those fans in the box make a racket, you might want to think about an effective but quiet cooling solution.
What video card depends on what you want to do. Both the above sites have lots of info. Get one that doesn't have a fan if you are concerned about noise.
Finally if you want a rea challenge and are interested in building a quiet box go to http://home.swipnet.se/tr/silence.html. Be prepared to spend some time.