As the title states, I'm looking for anyone that has built a server for their home. The reason I ask is, I'm looking to build one and wonder is it tough to do

The main purpose of it would be for streaming/storing all of my media (ie: Blu-ray movies, music, DVD's, etc) through a PS3 and laptop. I can't keep buying external hard drives and then trying to keep up with them, instead just centralize all of them.
So I guess my main questions to someone who has done this, is........
1) RAID1 or 5
2) At what point is overkill in reguards to RAM, video card, sound card and so on
3) Where's the best place for parts?
I have several questions, but I figure they'll come in do time
Thanks,
Mike