How can I get a modem driver for an obsolete modem?

I have a Motorola SB5100. I uninstalled the modem driver because it was corrupted. I've tried all the drivers on the Motorola website, but none of them will work. It may be because I have Windows 7(32 bit), but I doubt it. Where can I get one that will work so I can use the internet on my other computer?