not much going on here but I thought I would post this in case anyone else is going through the process.
I got a letter from Comcast saying that my cable modem was too old and needed to be upgraded to a DOC 3 cable modem.
looking at what was available at Best Buy I decided to try a Motorola cable modem-router-wireless combination. I thought it would be more efficient having it all together in one unit. it all seemed to be working well until I upgraded and added a cablecard network tv tuner and everything stopped working. after spending a lot of time trying to figure it out I moved the home theater system back to my old router and it worked fine.
I ended up taking it back and getting a stand alone cable modem only unit. everything seems to be ok again. the only issue I have is that the router cable modem link will only work if I power up the router first, then power the cable modem after. this is opposite what Comcast instructs you to do. I know that the linkage wasn't that picky before because the system used to come back without any attention after a power outage.
so for most uses the cable modem-router-wireless will work well, but if have a home theater system beware.