so if it has an express car slot, whats the next step??
Google for a product called ViDock which is an external casing for a desktop video card. There are a few versions range from about $200 - $300. The more expensive the case, the more powerful video card you can install. Of course you should find out what is the most powerful card you can install for each version before making your decision.
Don't forget, it's $200 - $300 + the price of the video card. Don't forget that you'll need to plug that baby into an A/C outlet.