Good news is the network of the VM works, with DHCP. I wasn't really sure if that was the case or not for Windows 98. So the VM boots up and gets an IP automatically.
Now, because I want to capture packets to reverse engineer the protocol, I've set up the VM in bridged mode so that 1) each VM gets its own IP that I can filter easily in captures 2) I can send packets to each VM from the host without having to sep up NAT traversals.
I've done this and VMs get IPs just fine. Then I launched #Wireshark, pinged some host on the internet and I saw the ICMP traffic.
Then I pinged one VM from another... They pong just fine, but in the pcap... Nothing.