for a laptop? really all i can do is go down a list, which no offense, is something you can do. as far as a new laptop goes though, dont get below a 460M. this is the list I'm using http://www.notebookcheck.net/Mobile-...ist.844.0.html
Any gpu above rank 70 will do the job, but i would look for something as high up on that last as you can afford since you're stuck with that GPU til you get a new laptop.

I strongly recommend a desktop for gaming if your situation will allow it. They're cheaper and much more powerful which gives a better performance to dollar ratio.