Hi. You don't have to upgrade (yet) if the HD 4830 is still good enough for your needs. The HD 7770 is a good choice if you want to upgrade. Any brand is fine although I recommend going with one of the least expensive card since the next best card, the GTX 650 Ti, costs only a little more. It is also a good choice especially if you can get it at a price similar to the cheapest HD 7770 since the next best card, the HD 7850, costs only a little more than it.