Try going to www.google.com to search for drivers for your modem. I know that there are specific driver search sites, but google will search all of these together.
Type in something like "Motorola sm56 pci speakerphone driver windows 98" if you're looking for windows 98 drivers for example. You'll get heaps of links, just open each up in new windows and find the most suitable one like that. Drivers are usually easy to install/update, depending on how confident you are with it. I'd say go for it yourself and save the cash!
Good luck