I have cable internet access, but i also elect to keep the modem, what with my Video Camera, Scanners, etc. you never know when it might be needed. I do a lot of editing of my videos of my grandchildren, and make up disks for my son.
LOL, then keep the firewire and pick up a cheap external modem for backup. That's assuming you have a serial port open. I use my Zoom external for a caller-id device. It pops up a windows on the monitor telling me who's calling.