vnetbios is nothing... vnetbios.vxd is a valid Windows 98 file and is located on the Windows 98 installation disk compressed within VNET9.CAB file. If you want to extract it manually, open Windows Explorer, find the file VNET9.CAB, right click it, left click VIEW. Right click file vnetbios.vxd, left click extract, choose folder C:\Windows\System and click ok.
This file should have been extracted automatically during installation of the os. The fact that is wasn't indicates you may have a bad installation disk.