Old Roman(?) Coin?

I have a coin which seems to be from Ancient Rome judging by the letters and I have seen similar coins on the internet from Ancient Rome. Could anyone either tell me who is on this coin/what year it is from, or point me to a website where I could find the information? Thank you very much in advance.

Here are the pictures:

http://i22.photobucket.com/albums/b323/chris_knows/coinfront.jpg

http://i22.photobucket.com/albums/b323/chris_knows/coinback.jpg

Is it possible for it to be a counterfeit even though my great grandmother found it (not exactly sure how)?