I remember having this issue before.  Go to add/remove programs and click on Add/Remove Windows components> check box  Add Networking services.

then try the following:

There's a Run command in 98 that I can't remember that verifies that all your 98 files are intact and if not the command can reload them...

I think it's SFC.EXE or SFC Type either of these 2 command from Start > Run

If your'e missing files this exec will recopy them back.

Do the above before trying to install the network adaptor.

Good Luck