My 8800GT actually gets 6.5K on good WU's like the one I just picked up. I get around 2.5k if I get lucky and not get stuck with 607X's.
Yea you can a 8800gt gets 4.5-5k and a e5300 gets about 2.5k a day. You can get 210k a month if you run 24/7 and if you only ran it like half a month you would get 100k. Get the fah gpu tracker its nice to run gpu and cpu off it and have no extra windows in your way.