EDIT: messed up somewhere. will re-do the math.
ok nevermind so its about 2.5GB each 90 minute movie yeah i guess you could easily go over it, thats like 100 movies, granted i doubt someone will have the time to watch that many movies in a month but add music downloads, youtube, hulu, music streaming like pandora, and general websurfing as well as gaming (which can be more of a bandwidth hog then you think) you could get close to going over if you werent careful.