Simply keep asking won't get you a darn good solution. A bit of work on you own will simply do.
First, calculate how much power you need.http://extreme.outervision.com/index.jsphttp://extreme.outervision.com/psucalculatorlite.jsp
This will give you the idea if you need a better PSU, or simply get a less power consumtion GPU.
Warning! draw too much power from rated PSU will blow away your PSU. Then damaged PSU will take computer components along. So don't be cheap on PSU.