The reason these drivers exist is because your OS has crap stock drivers that will work with everything, the extra drivers provide code so your OS can take advantage of the awesome resolution or other stuff your graphics card or monitor can do.
I'm not sure if you mean external PCIE stuff, or something like a USB to video adapter like this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16812240021
I hear they work decently if you need to add another monitor and don't have any more outputs on your card/mobo