If the other computer has the Windows XP OS installed, you will need to run the network setup wizard again and set the "workgroup" to MSHOME or whatever you prefer. Then on the Windows 98 system you will need to change the workgroup accordingly, reboot and setup internet explorer to use LAN, it may take about 5 minutes for it to detect the proxies, but if you keep getting the error page right after hitting F5, you may need to reinstall the drivers, disable the hardware enable and reboot.
BTW If this works theres no charge, we are comrades.
Are you using the driver on the OEM cd? Here are the updated drivers, if these don't work, you had better make sure the link lights are on and showing activity.