EVGA 02G-P3-1559-KR GeForce GTX 550 Ti (Fermi) 2GB 192-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card $169.99http://www.newegg.com/Product/Product.aspx?Item=N82E16814130652
You could get this card and as it will give you the performance boost you want and work well with your cpu. You didnt list any games that you are playing and the newer ones out now have a wide variety of requirements . Your cpu (if you are correct) has a good speed (3.0ghz ?) and it will take a decent video card to bottleneck it , and I'm sure the high end cards will. If you are playing Skyrim then with this card you will get around 50fps on medium to high settings.