If it is just a plain old modem (dsl or cable) then there really isn't anything to configure. Any "modem" with any sort of configuration in it will basically be a modem with some sort of router fuctionality. Some modems that are out now (such as the speedstream 5100/5200 for adsl) have some configuration options built into them that you can access via a web browser (when the modem is connected directly to a comp). Some higher end modems out there that have console ports for configuration.
Yes, BB modems are configurable, just like 'ordinary' modems.
My experience with Broadband Modems is this: I signed up for a 'broadband connection' with my ISP and after a couple of weeks during which they had to do something at the telephone exchange I got a package through the post containing my 'broadband modem'. This was a Sagem F@ST 800. The Sagem is a little box that connects to, and is powered by USB, so it does not need an external power supply.
My first broadband experience consisted of my Windows 2000 installation containing my email and personal documents becoming more and more infiltrated and infected with BUGS - trojans, and all sorts of malware. I tried every cleaning option I could but it just got worse and worse! :? Symantec anti-virus was telling me that my computer was sending out crap emails every time I was on-line. Eventually I had to format the partition (after salvaging my data) and reload all my programs. I now use an anti-virus program (Free-AV.com), ZoneAlarm and Microsoft anti-spyware beta and have not had a problem since. You need a fully-patched system with up-to-date virus definitions etc. to venture on-line nowadays. I had not taken protection too seriously but I do now.
I then began to find that the broadband ADSL modem was becoming a little bit unreliable. The connection went up and down; sometimes the system was reporting a valid connection but surfing was not happening and the situation was getting annoying. I have more than one computer including a laptop and also a printer, all of which are connected by ethernet using a Belkin ethernet switching hub. :idea: I decided I needed a broadband router instead of a modem. My investigations on the Internet did not reveal much information about these things. I ordered a recommended Router from my ISP, for about £45(GBP). On their web site the Sagem was awared 5 stars for ease of use, features, etc. The router was awarded only 4 stars, but that did not put me off. The model I got was a Thomson Speedtouch 536, which has a single Ethernet connection, or you can use USB instead. I went for the Ethernet, because I wanted to be able to connect from any computer. Other models in the Thomson range have 4 ethernet connections, or wireless which I didn't want because I didn't feel the need for personal irradiation.
On the CD that came with the BB router, the 'easy set up' was for the USB connection, with Ethernet was in the 'advanced' section. The USB featured Ethernet emulation, but I wanted the real Ethernet functionality. THe Speedtouch is configured using a web interface. I set an administration password, and keyed in my ISP personal account details and password, although before all this I had to press the reset button on the back of the router to reset it to the manufacturers original settings.
The result of all this aggravation was a vastly improved browsing experiance with a BB router compared to a BB modem. When you switch the Speedtouch on, the Power LED comes on first, followed by the Ethernet LED. Then the DSL LED flashes while it sets up an ADSL connection to the local telephone exchange. After a further few seconds, the Internet LED comes on and you're away. The router functions as a DHCP server, which means that it can set up IP addresses for your computer(s). If the connection goes down, the Internet and DSL LED's go off, but the router reconnects itself automatically. When the connaction is down, or is going up and down like a yoyo, I can see what's going on from the state of the little green lights much more easily than with the Broadband modem.
I'd recommend using a router rather than a modem any day even if you only have one computer. The Ethernet port on the Speedtouch router is autosensing which means that if you really need a crossover cable but just have a standard one the router wil cross the connections over itself automatially. This situation might arise if you have just one computer and no Ethernet hub.
It might seem a lot of aggravation to set up the router, but using the router compared with the modem is so much less hassle. I can connect to the Internet from any computer using any OS. Connecting to the Internet with the router is much like being on a proper metwork, rather than having to wait for the modem to connect up every time. THe router takes care of itself.