my sister has comcast cable and she doesn't need any kind of software at all. she runs os 9.1 on a clamshell-style ibook (tangerine), and hooks straight into the ethernet modem that comcast supplied. no software, no drivers, just working broadband.
are you sure you need the software? most tech support people don't know what they're doing, and when it comes to Mac knowledge, they're in negative territory.
try just hooking into your ethernet modem, power it down, shutdown your Mac, power on the modem, then start up your mac.
disable the software before trying this.