I would practically have to hold your current power supply in my hand to make a judgment about its quality.
Some of the AMD / ATI mid-level startup new gamer GPUs have been a good comprise between performance and current demands from a PSU, but you can practically only find that class of card as OEM parts, from the likes of Dell, HP, and your PC's source company, at inflated prices. Last offered by AMD as the HD 6670, sold after that without actual physical change as the HD 7670, and more recently as the HD 8670, that is a serviceable unit, although overpriced now.
Newegg still has some of these $80.00 parts for sale: http://www.newegg.com/Product/Product.aspx?Item=N82E16814121645
You have to be in Canada, China, or The USA to shop there.