Wow, that rant felt good.
Turns out, all I needed to do was UNPLUG the cable modem from the wall (I went ahead and disconnected the ethernet cable, and the coax just to be sure) for 30 seconds. Did the same for my laptop and my wireless router. Just hitting the on/off switch on the cable modem wasn't enough to reset it. Why the Comcast rep didn't mention that fact is beyond me. (I guess that's part of the fun of being a tech support person.... and we've all probably heard tons of funny stories about stupid things users do in response to things tech support people tell them to do. (although I'm not calling myself stupid here))
I think I'll still play some XBOX with my son for a little while after I get back from taking my wife on a hot date at the IHOP. (nothing in the world like breakfast for dinner)