I would get the 7900 gs just cause of the price/performance ratio over the 7600gt, plus the oc ability with stock cooler (I hit 550/800 easy, a little higher with vf900).
It's going to be hard to even scrape together 150. I was seriously looking into a 6600GT at one point, but decided to do a little better.
A 7900 is WAY out of my price range. I don't care about its price to performance ratio, or its overclocking ability. I just want a good, solid, inexpensive card.
Thanks for the help everyone, I think I am going to get a 7600.