I think you should give yourself the option to add a second card later in Crossfire.
1. Get a 750TX from newegg (same price as the PSU you picked, more powerful, better reviews).
2. An RC-690 or Antec 900 case would be great because they have good cooling. I don't trust that Thermaltake with only 2 fans to handle a high-end gaming PC.
3. Replace the motherboard with a P5E Deluxe X48 or GA-X48-DS4. The P5Q-E P45 creates a bottleneck with two HD 4870 cards in Crossfire and slows them down.
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