Works for Win2000 and WinXP.
Go to Device Manager and select HSP56 MicroModem. Select "Update Driver" installed by WinXP during initial install. Force it to install this driver by using "Install from a list or specific location". Then select "Don't search I will choose the driver to install". Select HSP56 MicroModem from the list and select "Have Disk". Browse to unzipped files and continue as required. WinXP will warn you that it's not digitally signed and has not been tested for compatibility - but I used it anyway and it WORKS.