What's a decent laptop for gaming?

I've been searching for a gaming laptop for quite some time but can't find something that fits my requirements. It has to be less than $800 and has to at least be a 15 inch display. I just want something that can run all games on lowest-medium settings. Games like torchlight 2,battlefield 3, grand theft auto 4, fallout 3. What are some recommendations of laptops that can fulfill my needs?

Thanks for the help!