I would blow off the internal modem and ask them for an external. (NOT the USB version, which sucks) That's what BellSouth gave me, but I had to INSIST that was what I wanted. I got some sort of Alcatel external that I have patched into my Netgear router. I'd have to look up the model number of the modem to be sure which one it is.
They hemmed and hawed about them having to install it, but the installer called in and got the OK for me to do it myself. Set up was easy.
You'll need a network card installed if you don't have one already.
I have had this setup for right at 1 year and it has worked flawlessly. I got lucky and now that I've had the service for a year, the modem is MINE!
As for finding an external DSL modem out in "the field", I haven't seen one on the shelves here, but I live in a small town. It will have to be DSL specific, but you probably know that already. The main advantage to external: you can shut off access to the computer/Internet by simply unclipping the network cable between the computer and router or switch/hub.