My laptop's graphics are pretty bad, can I get an external graphics card to boost its capability?
Not yet. There was talk last year about a product from Asus to plug into the expresscard slot, but this never came to fruitation.
You can get a vga port on a docking station by belkin, but this simply acts as another socket rather than a boost.
Is there any way to boost its power?
The best way is through more ram, but this will only give a faster game play not smoother.