I had a similar problem, w2k detected my modem as a 3com t1 modem when I really had a 3com winmodem sportster model 0481 which came with my micronpc. This is about 2 months ago or so. I never go it fix but maybe you are luck. I am guessing you don't know your modem Serial # right?
Open your case and take out ya modem you will see three set of numbers.
1. you will see 2 set of numbers side by side some thing like this
0001256025860658 srn#000056830 (the second one will be your serial number)
2. The third number is on the metal that goes into your case, you will see something like
Model = 0481 (this is not the serial number but you can use it to search
www.hotbot.com to see out frustrated customers looking for drivers)