You probably don't even need the ICS.
I agree with Johnny to get cable internet. This would break down to roughly $10/roommate for the 5 of them. Most cable companies have bundle packages for cable TV&Internet.
At most, you would need something like: 1) Cable Modem (if it's not provided by the cable company), and a Linksys Cable/DSL Router with 8 port switch (BEFSR81 is the part number). You can go to http://www.linksys.c...cid=29&prid=604
to see what I'm talking about.
This is of course they want to have one computer area in the house, or if the house is wired for networking. Otherwise, you'd probably want to introduce a wireless access point, as it'd be a pain to run cable all over the house.
Well, that should be a start.
Hope that helps.