Well, you are not going to find a direct link to download the driver, at least from Windows. But, you can right-click on My Computer, Properties, go to Hardware tab, then Device Manager and a new window pops up. You can see a list with all your hardware info you need. Scroll down until you find audio, video... click on the '+' on its side and check there for the name of your audio card. If you want maybe to find more try right-click on it and select Properties.
Hope this is not confusing

When you're ready post its name here and we will search for your driver, hopefully. Goodluck.
Regards
EDIT: Not sure if Windows 98 has the same procedure as XP, but it should be similar. Post again if you encounter problems.