Sometimes, Windows exhibits some latency in showing other PC's in Network Neighborhood. Don't ask me why. It can take awhile for another PC to show up sometimes. Make sure you have a crossover cable. There is a difference with a cat 5 cable that may have come with the network card.
Crossover cable is used between two machines.
A straight thru cable is used between machines and a hub. Everything else you try is useless until you are positive that you are using a crossover cable. However, I do have a hub also and connected it to that, no luck. Tried the ping, no luck. It looks as though the Win98 is working, as I can see my the Win98 machine in the network neighbourhood, but this is on the Win98 machine.