"light to medium games" does not really describe things too well. What do you have for a card now? Need full computer specs, case size/model/brand, power supply brand and model, what Core 2 Duo, they range quite a bit in speeds? Even for a fast one, you don't need to go over something like a GT 730 or AMD Radeon 7750, something from that range and cost (for a used one, new they are a bit pricy for the speed).