I thought Lucent was a telecom company. Anyway, 4 x 120 mm fans sounds good, especially with two HD 4850 cards in there.
Yes that PSU is powerful enough for HD 4850 CF. Minimum recommended is 550W, according to this:http://www.newegg.com/Product/Product.aspx?Item=N82E16814161244
Too bad you bought first and asked later. Not a winning strategy, you know... Anyway, you did good. I'd have recommended a few minor changes (Corsair 650W, WD 640GB Caviar Black, LG burner), but it's too late now and what you got is good enough anyway.