GPU mining is way outdated, I started mining with 2x 7970's back in March and I've yet to break even. If you compare the cost of GPU's to the competition out there:
AMD 7970, which mines at 600mh/s for $350 = 1.9mh/s per dollar
USB Block Erupter, 330mh/s for $100 = 3.3 mh/s per dollar
BFL Jalapeno, 5000gh/s for $275 = 18mh/s per dollar
If you follow the mining community closely, apparently even ordering a Jalapeno today won't be profitable because by...