1. if you plan to purchase a card in summer of 2011 then there is no point discussing this. Both ATI and Nvidia will have new cards out by then and the whole market in terms of price, performance, and options will be changed beyond what anyone can predict.
2. you need to upgrade your PSU. I would suggest you start saving your pennies and get a
450w+ unit from seasonic, corsair, or antec.
500w+ from xigmatek, ocz, enermax, silverstone.