Not much you can do for laptops.
If you have 1 gig of ram upgrading to 2gig will help some on games and multitasking.
Have you cleaned the heat sinks vents lately?
Blow compressed air into the heat sink outlets and remove the dust, hair, lint buildup and it should cure your overheating problems.
This will blow it back into the fan and you may have to use hemostats, toothpicks etc. to get the compressed clumps out.