That is not nearly as much as it sounds like. It really just depends what you do online.
The aggrevatingly nitpicking portion of my brain would look at your contract and see if a limit is specified (I have never heard of there actually being one) and then intentionally go over (preferably by downloading and seeding every variation of my favourite distro 24/7 so they can't claim copyright violations are implicit) so I can call them threaten to sue and get my net turned back on with a few months free (though I am good at yelling, YMMV). Unless you agreed to such limits (in your contract) imposing them is at the very least questionable. That said I would already have another provider lined up if I got as much as a warning from my ISP about such hijinx.
That said, good luck getting this feature, it is one that makes a whole lot more sense than a lot of requests I see.
Hmmmm, the thing is, I very might doabt he IS downloading Linux distro. And I am sure they put a "we can change network practices anytime we want" in the contract. As for Cox, they DO give you a bandwidth monitor, and I think Comcast does too. This is really about bandwidth use and what the average person uses for lawful practices. Theres a set amount of bandwidth to go around, and the more you use, the less there are for others. Setting caps is common place in other countries and common here with cell phone data plans and such. Alot of people are having knee jerk reactions about about this because their being caught with their pants down because....all of a sudden someone is telling them "No, you really cant Seed 1000+ people 24/7 on bittorrent". Times are a change, instead of thinking lawsuit, you may want to actually look at your usage practices. :-)