I have been searching for what type of psu I should get for my new computer for a low/mid range video card(i am on a budget of a about 150$ for a psu and card together and it has got my brain racing). Found tomshardware and thought it wouldn't hurt to ask here(Don't know a lot about computer hardware but know some).
The stock PSU in the Gateway would be fine to power a 8600GT 512 with DDR3 RAM (the DDR3 is appreciably faster than the DDR2 version) You'd only need to upgrade the PSU if you went to a more powerful graphics card.
Great buy right now on a PSU for single card solutions is the Antec 430w Earthwatts http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$30 after rebate