Remember that's 175w each card, but you should have plenty with that PSU. actually 175w was the reference 5850. The non reference cards are rumored to run on 10-15% less than that.
Yea the GPU i am getting is a super cool quiet one so prob wnt use less because of the extra fans running on the chip. Also faster then the standard one, but i was only planning on running dual anyway so either way should work smooth