[newbie] NIC cards and Cable modems

[Flight16]

We'll be getting a cable modem ISP before the end of the year, and I was
wondering how compatible they are with Linux.  Are they a pain to set
up?  Can you get an external one that hooks up to your serial port like
analog and v.90 modems?  And when you do set it up, since it's sort of
an "always connected" sort'a service, would you configure a network
setup instead of a dial-up network setup?  Thanks for your time.

Flight16