the gt 240 will be significantly faster than your current gpu, but dont expect to play the latest games at full detail. It is as fast as my 4 year old 8800gts which was only the second fastest card out when i bought it. Depending on the specific brand and 12V specs on the psu may determine weather 510w is enough for a better card or not. Also, what CPU do you have, what motherboard do you have and how much ram do you have? Some older motherboards arent compatable with newer video cards.