I'd recommend against this unit. you are better off buying a seperate cable modem and seperate router. this avoids the situation where you have a single point of failure. for example, if you cable modem goes down, your still be able to transfer files from computer to computer on your network. also, if you router does down, you can still connect directly the cable modem to work on the internet. this assumes you aren't running a switch.
anyway, of none of these points matter to you then get the combo unit.