I have a SB4200 which I believe is the same . For networking I got myself a Linksys Wireless G Broadband router WRT54G (Amazon was the cheapest). I use Telewest/blueyonder as ISP and now that they have taken off the MAC address registration no messing about with the ISP when I installed it.
Hooked via ethernet from modem to router, hardwired 2 X PCs to router and another via wireless no probs . Only thing to remember is to add secuiry on the wireless link otherwise anyone in range can access.
The router is accessed via an Ip addy using internet explorer and you can play around with settings but it works OK straight from the box. The documention is "fairly good/mediocre". However doubtless peeps on here and other forums can help if you get stuck!!
Cheers & Happy Christmas