Video card upgrade for a notebook?

I have a Dell Inspiron E1505 with an ATI Mobility Radeon X1300. I'd like to upgrade it but I have no idea what to look for or if an upgrade is even possible. I'd like to be able to run something like Half-life 2 Episode 2 without having to dumb it down. I don't need anything too high end. After a certain price it'd end up easier to just by a game console. Suggestions?|||No, not possible.