You can try to find an Ethernet card that you can connect to the motherboard.
All it needs (but that might be impossible requirements unless you buy a secondhand PC with it):
- fit on your motherboard (that's easy if it has PCI)
- have a driver for Windows 98
I'm sure those existed in 1998. But we're 14 years later now ...
I recently took an old Compaq Impresario with Win98 out of mothballs. It was manufactured in the late 90's. There is no eithernet outlet to hook up to my DSL router and my attempt to download software for an Netgear USB wireless device was not successful. So it appears it can only be used for dialup internet service. Is there a way to convert it so it can be attached to my router?