Tonight, we bit the bullet and called Comcast about our seemingly never-ending connectivity issues. I've gotta say, given all the horror stories we've heard (from multiple sources), we were expecting the worst. But the guy we spoke to, "Ben," was accomodating and seemed knowledgeable enough, and got us back up ... for now. He also left us with instructions to call every time it went out, as soon as possible after it went out, in the hopes of diagnosing what was going on.
So ... we'll see. But I'm hopeful. :)