You should be able to play all games at least on high (not ultra) with around 30 FPS or more. Any games that are a couple of years old will be maxed out. For more difficult games a small RAM upgrade won't hurt, but it's not necessary as 4 GB isn't perfect, but it should be enough.
With your current configuration , you will be able to play most games in Ultra and all the games in HIGH settings except for you ram . Try buying an 4 gb more ram and then you will be able to play games at the best of your configuration.