Because of the change in prices from the time of the OP and the lack of low profile 8500GT at newegg, you'd be better off using a HD4550. http://www.newegg.com/Product/Product.aspx?Item=N82E16814121281
*EDIT* i should have added that if you want better performance depending on budget you can add a new power supply and a different graphic card, it would depend on what you're doing with the system and your screen resolution.
thanks for the answer
if I could, of course I would rather get a stronger graphic card but I really do not know how does the power supply work in all of this............
so basically, you plug the CPU power plug to the power supply?