WTF 40GB per month? What is this 1998? Jesus each website you go to nowadays is easily 1MB or over. My network at home has about 5+ connects connected to it often. I would easily go over that every month, doing nothing illegal or against my ISP's TOS.
ive heard the rumors that many ISPs are starting to get more aggresive in limiting bandwidth, comcast has already joined this bandwagon. applying a choke to bittorrent traffic, and more monitoring of the bandwith caps