Aim Far,
If you have the SM56 Speakerphone Modem (Data/Fax/Voice) there is a WinXP Driver for it:
SM56 Speakerphone Modem
If you have the SM56 SoftModem (Data/Fax) there is a Win2k Driver that should work under WinXP:
SM56 SoftModem
If you spend any amount time online, you should really think about getting a full modem, Softmodems (also known as WinModems) are not really modems, they are just the jacks for the phone. Your CPU does all the work for generating the tones for the modem. That is why people with WinModems, always notice how their computer slows down while they are online.
U.S. Robotics makes some of the best modems for people that spend a lot of time online. Their PCI Performance Pro line and their external modems are excellent.
Take Care,
Richard