Nope, if it is external then it is a controller based modem; not a winmodem (contolleress and cpu dependent). Your likely problem is your available memory. The more crap you have running in the background the more your surfing will slug depending on what you are doing. Hit cntrl + alt + delete and see how much stuff is running. A lot? Go to start/run/ msconfig and select the startup tab. Disable (uncheck) whatever is unneeded/unwanted at bootup. Example: Loadpower profile, scheduling agent, findfast, office startup, yahoo pager, etc... I'd leave scanregistry alone for one...
I'd start there first. Get more memory if you have to. Windows 98 = 128mb best. More is overkill. Defrag your harddrive, set it as network server under performance, and set your virtual memory to 128 or 256mb for min and max. That might help a little also.
LOL!!! I guess I should've read his specs a little better. After 12 hours at work I miss the obvious sometimes. WHoo00. More sleep less coffee..