Update:

Comcast says their limit is 250 gigabytes per month, bidirectional, as we had already discussed.

What surprises me is that there's no way for a customer to monitor their household bandwidth usage. (I asked.) Clearly Comcast can track a given client's bandwidth usage (they have to in order to enforce the cap), but keep that information secret from the users until they bust the threshold. How terribly unfair.

I suppose could put a dedicated proxy computer between my network and the cable modem, and track usage that way. But I don't have the extra computer and don't want to do that anyway.

I like being able to stream instant Netflix on my Xbox or my Tivo. I wonder how many of those I could watch in a month before hitting 250gb.