The SMB systems are pretty bad. You're better off just looking at them and then moving on.
I don't care what you say about not wanting Seagate. Right now, WD is losing the battle. The new 7200.12s and Samsung Spinpoint F3s are faster, quieter, cooler and a lot cheaper. They're also very reliable.
An Intel CPU is way out of budget. The cheapest CPU I would recommend is the i5-750, and it's $200 by itself, or about $40 more expensive than the best AMD CPU. The boards for it are also $50 more expensive. That's almost $100 sucked out of the budget for no real gain.