i was playing games with the 7600gt on a 300w PSU non stop for about a month until i got my 500w psu. it worked fine, flawless, I didnt have one problem. sure i was pushing it, but it was holding out just fine. don't worry... get the psu when u get the money, so you get a good one. not a crappy $20 that will ruin your system.
yes, a 300w psu. 7600gt. it was fine...