Dragonlich

A few comments:
- You might get a cheaper motherboard; this one might be a bit over the top with goodies you probably will never use. The motherboard is indeed crossfire, which means you can't use two Nvidia cards; you could use two Ati cards, though.
- I dunno about the Antec PSU. It's probably good enough, but you might want to look at some review sites to check out other options. I have a Corsair 520W PSU with a similar system; the reason: it's really quiet.
- The Scythe Ninja is a good cooler, especially if you want it to be quiet. The standard 120mm fan is a bit loud, though; I replaced it with a nexus fan. But depending on the sound level of the rest of the system, you may not notice the difference.
One tip: the standard (intel) heat sink mounting system doesn't look very secure; In practice, it'll probably be fine, but having that much weight wobbling around is a bit scary. Just in case, I got a thermaltake bolt-through kit, which works fine with the Scythe cooler, and is much more secure.
- The harddisks... two 500 gig harddisks? Are you going to run them as a RAID disk, and/or do you need that much space? Depending on the raid level, you either get better speed and less reliability; or same speed, only 500 gig of space, and better reliability. If you don't use raid, the second disk might be empty for a loooong time. (Personal experience...)

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One addition about the memory: if you're going to get 4 gig, you'll probably want to use a 64 bit operating system. With 32 bits, you'll only be able to use about 3 gigs of memory.