download limit

I am considering a wireless high speed Internet connection that is new in our area. It is my only highspeed option except for Satellite. The problem is a 2.5 Gig monthly upload download limit and $20.00 a gig charge over that amount. Is there any shareware or even freeware that will track upload and download over a day or longer so that I can get an idea for what I am in for.

Dennis