there are a few things
be it a desktop or laptop. check the bios to see if there a setting for video ram or some intel based chipset you can have one or 8 megs of video ram.if your bios has that setting change it to the larger setting and then see if it still lags.
with onboard chipsets it going to use system ram so the more ram you have the better it is for the onboard video. in the game video settings there are things like aa and other poligons that you can turn off or down to make ther game run better on low end video cards. I would look at the games help board to see what people set there setting on to help old older pc.
Does an ursine quadruped void wastes in an arboreal environment?