Are there any external graphic cards? If yes, are they connected through a USB cable? What’s the best external graphics card?
Yes it is possible and the do make them. They connect to your computer via USB and use DVI (Usually), but if your computer is using VGA they usually come with a VGA adapter
Here is what I would recommend: http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4545270&CatId=317
Also here is a link to google shopping search, to give you a idea of price and give you some options: http://www.google.com/search?hl=en&tbm=shop&q=usb+graphics+card&oq=usb+graphics+card&aq=f&aqi=&aql=&gs_l=products-cc.3...42671.47765.0.47918.104.22.168.0.0.0.0.0..0.0...0.0.