It's entirely dependent on what you want to do as far as gaming.
If you're looking at playing a game like Skyrim on max settings, you're more than likely going to have to drop some coin for a build. (You also have the option of buying a pre-built "gaming desktop/laptop" but unless you can't click legos together, you're really better off building your own.)
Older games, like Age of Empires or Modern Warfare 2, you might be good on.
If you give us a little more detail in what you're aiming to do, then we'll be able to guide you.
Also, if you want to figure out where you stand with your current hardware (Which I don't know much about at all.) you can check out Can You Run It?
and it will gauge your system against the listed requirements of a game.