i don't know if this will help you when i first setup Ubuntu on
my machine i had everything hooked up once the operating system was
installed and booted for the first time the operating system
recognized the modem and all hardware hooked up to the computer and
installed the drivers for each if you didn't have everything hooked up
before hand you might want to try installing again but this time hook
everything up first.i use a cable modem and it was there ready to use
after the install.