If you're going to record TV shows and turn them into DivX or whatever you should get a Q9550 instead of the E8500. Same if you play Flight Simulator X. Apart from that, the E8500 will be fine.
The RC-690 has great cooling. I'd prefer it to the Antec 900 because I watch movies a lot and don't want annoying lights.
The retention bracket is useful if you move the PC around (LAN parties, whatever) or if you hate push-pins.
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