I'm not a huge gamer so my advice might not be worth all that much. One thing I would suggest is that you provide a little more detail - someone else who knows more will probably be able to give you better advice.
I would list the following:
1) Your budget. It's easier to make recommendations if you know what the person is willing and able to spend.
2) What games you want to play on it.
3) What screen resolution you hope to run and what frame rate you consider a minimum.
4) How long you plan to make this system last before you replace it. Some people build a new gaming computer every year. Others know that their next computer will have to last them for a good long while before it's replaced.