Evolution of Windows Networking

What has changed in Windows networking over the years that might affect connectivity among peers? We have small Windows networks in branch offices on which a Sybase SQL Anywhere data base is running. Most of the PCs run Win95 or Win95B; when we add Win98 PCs to the mix, the new PCs are unable to find the data base. The protocol by which the data base clients see the data base is NETBIOS; have there been upgrades to NETBEUI that might affect this? TIA.