After I installed Windows XP, the OS couldn't find any drivers for my modem. My modem was installed as a standard 56Kbps modem and worked very slowly, although the speed and connection settings were correct.
To solve this problem, I decided to install my previous Windows 95 drivers for the modem. I right-clicked My Computer, then Properties. In the System Properties window that appeared, I clicked Hardware, Device Manager. I opened the Modems category in the devices tree and selected my modem (i.e., standard 56Kbps modem), then right-clicked and selected Properties, Driver, Update Driver. When I received a warning message during the driver-setup procedure that stated the driver wasn't certified, I selected Continue rather than Stop installation. The driver installed successfully, and my modem resumed working.
If you run into a similar problem, you might try installing your old drivers before you buy new hardware. Although not all your old drivers will work, some of them might.