someone will reply with a link to "Which cable do i use"
ok, so you ahve a cable modem and a router?
you will use cat 5(or cat5e) straight patch cable.
both straight patch and crossover pathc will be twisted pair.
I actually think that some routers and/or nics will still take a crossed over cable and will adjust themselves to use it normally, but in this case, if you are buying new cable, get a straight patch.