I helped my Dad installed cable modem at his house today. He picked Comcast. I use RCN myself, so I am not familiar with the Comcast setup. The documentation said it requires a sign-up process when connected for the first time. So I called their tech support. While he is walking me through what needs to be done, and was waiting between steps (windows IS slow) I asked him what's the ratio of Windows vs Mac OS call to the tech support line. He said eight to one. Not bad -- there are macs out there !
Oh -- if you are interested in how Comcast's cable service works, during "installation", I have to connect out via a proxy server. The proxy server asked for a one time signup identification, which is the account number and the last nine digit of the account number. After the initial setup you can switch off the proxy. The tech said the information is "recorded on the cable modem". I am not sure about this, maybe a flag is set? I am not sure. But good news is you don't have to install software to do the installation/registration.
Once the account is setup, I moved the modem to a wireless AP + router and everything is all set to go.