Graphics card on Toughbook CF-18, can you change it?

I have a Panasonic Toughbook, model CF-18. I recently had the Hard Drive fixed, because I couldn't install anything on it due to a lock by the previous user. Now that I was able to install things, I tried installing a game, (Namely, the first Assassin's Creed for PC) on it, however after the installation it would not open, because it said the graphics card was too low. I was wondering, is it possible to change the graphics/video card on the model CF-18 to a higher model? If so, how would I go about this? I'm pretty clumsy, and tend to drop things (good reason to get a Toughbook in itself) and I would rather have a walkthrough rather than trying it myself. Thank you all in advance.