You should be okay with the integrated ATI 780M (HD 3200) which is based on the older HD 2400 GPU. Just stay away from any graphics demanding games published after 2006.
Then increase your budget to get a laptop with a more powerful GPU. If you think the RS780M can't cut it, then the GMA 4500 certainly will not.
I don't keep up with laptop GPUs so my best guess is to buy something with an ATI Mobility HD 4650 or GeForce 9600M GS get decent performance on a laptop.
You can take a look at the ATI Mobility 4570...The laptops that come with that don't have high price premium...
Dell has laptops with that graphic chip...