Installing a graphics card is as easy as adding ram, they are the first things a novice can do for themselves. Dont be scared, just get an anti-static bracelet ($5) and a flashlight to see what you're doing.

Back to the original question; most better video cards these days can support dual monitors. It is real easy to tell: does your computer have 2 places to plug in monitors? If not, may I suggest getting an 8800gts.