dunno if this has been asnwered yet, i saw a lot of unrelated stuff...so here goes:
where are you located, joe? i'm in philadelphia, with verizon. in the dead center of the city you'd think i would face similar problems like flaky bandwitdh and disconnections, but i havn't have a single problem with it for the 6 months i've had it. i have the DSL modem, and also a belkin router. if anything DOES go wrong, unplug the modem for a few minutes then turn it back on, with a router or anything else disconnected. let it re-commit to the system, then plug everything back in. make sure you don't have any of those DSL filters on your modem's line, and make sure all phones in your house are comming off of those filters.. they WILL interferre with your service. then, test out your personal firewalls.. by default, they should allow the modem's connections..
you can also double check your network settings, something might have changed them wrongfully.. you want your IP, gateway, domain, all of that to be 'automatic'. if you are going through a router, have the router clone your primary computer's MAC address, and then let the router handle your IP assignments. i can give more in-depth info if you need it.
kona, you have to pay comcast a whole lot more money to get anything other than crap speeds, at least around here. for 30$ a month, my verizon service is amazing. you get the MSN access (which is like, a 20$/month value) and that service has a lot of features i use CONSTANTLY.. from the encylopedia, to finances, to the online address book that will sync with my cell phone.. it's a great deal no matter how you look at it. and, to mirror those aol commercials taht say 'a basic high speed internet access gets you online but doesn't take you anywhere), comcast put me through constant customer service hell, any kind of system help became costly, and they don't do anything for you farther then a 'my comcast' webpage and a personal website. for the buck, verizon is a steal. it may not be as fast in the higher end, but it does what it's gotta do. get me online fast.