What are some good Custom PC Build sites?

[cloud1161]

I'm thinking about building my first PC once school is finished.  I'm looking for sites that have like part prices and maybe some tutorials/videos comparing builds and stuff.  I'm trying to keep it pretty simple for my first build, I would like to put a quad core processor if they arent too bad (under 100), but thats probably wishful thinking.  I'm hoping to keep the whole bundle under 500.  I don't need a monitor or any accessories.  I'm kind of leaning towards AMD processor/motherboard because every computer I've had has been Intell, so I would like to try something different.