Not quite sure about DHCP (or indeed, what it is!), but I also have a Netgear router, and as long as you set it to automatically get the IP dynamically from the ISP, it should sort itself out, DG. Try going into the router settings, and look on the Basic settings page. You should find, under the log in details, a tick button to automatically select the IP dynamically from the ISP. Try that and see if it makes any difference.
I agree about the benefit of additional security, but it does come at a price, as you do have to fiddle about opening ports, and allowing services for P2P networks. You also have to make sure that your P2P client isn't set to automatically select a new port each time it starts, or you will keep having to reset the router to the new port.
My point is the same as DG's, in that an ADSL modem requires very little maintenence, and is simple to set up. There are obviously pros and cons with each, but for a single PC, with no networking requirements, disregarding the security aspects (which a good software firewall will take care of), a router isn't essential.
