Computer specs question

Here is my current computer

Intel Core 2 Quad COU Q6600 2.4 GHz
4 GB Ram
Vista 64 Bit
Nvidia 8500 GT

I can run some games, but I want to improve my rig. Would buying a new a graphics card be enough, or would it be wiser to save and then just buy a new computer all together? In other words, is the graphics card the only thing that is holding me back from having a really good rig, or is my processor not powerful enough either?

Graphics card easily. The rest of that should be more than well enough to play most games (especially any console ports) on high settings.

Depending on how much you want to spend you could make some big leaps from upgrading that.

What would you recommend?

What's your budget?

You can find much better cards for less than $150. Check out sites like newegg.com and there should be plenty of options.