I think you're pursuing the right course. See whether the new modem takes care of the problem (could be a simple hardware problem -- my guess is no). If you get another ISP, the new ISP may give you an Ethernet card (mine did). Ask (it can't hurt). And if you do decide to go the network route, you can always get a wireless firewall/router. That way, if you have other computers in the house (I have a ton), getting them networked won't require drilling holes and pulling cable. Cheers!
The promised new modem arrived, a Westell 6100, but it didn't solve the problem. I still couldn't establish a DSL connection (although, maddeningly, that telephone line was working fine, and I was using it for dial-up surfing).
After some more service calling, Bellsouth said that due to the hurricanes, their DSL service was down, so I'd have to wait until the 14th, when it should be restored. I waited. No progress on the 14th. On the 15th it still wasn't restored.
Back on the phone with the tech guys. To make a long story shorter, they sent out someone to check my line. It's okay, but -- this sounds crazy -- a wire in my phone jack had come lose and it was just whacked enough to kill the DSL connection, but voice was okay. As soon as the guy adjusted it the problem was solved.
So my problem didn't have anything to do with Service Pack 2. Nor was it related to my old Alcatel modem (although my new Westell seems to be somewhat faster, so I'm glad I upgraded). The only sensible thing I did in this whole mess was decide NOT to un-install SP2. That would have solved nothing. And Bellsouth is okay. It just took a long time to get to the root of the problem.
End of report.