Lan problem

I had three computers W98Se - W95 - W95 using a simple LAN
with PCI Ethernet cards (BJC connectors). The LAN worked
well. I have since upgraded one of the computers to W98SE
(drive formatted and fresh installation). When I checked
in the Network Neighbourhood, the Workgroup of the
upgarded computer is visible, but the actual computer is
not. I get an error message stating something to the
effect that the computer is not connected or folders are
not shared. I have gone through all my settings and as far
as I can tell, they are the same on all three computers, I
have installed file and folder sharing, Client for
Microsoft networks, IPX/SPX protocol, Netbeui and TCP/IP.

Is there something that I am missiing? Device Manager
indicates that the NEC card is working and have checked
using one of the other cards, so it would appear not to be
the hardware. Do I need to update the drivers for 98SE?

Any help would be greatly appreciated,

M