You are just connecting the two 98 cps together, one has a regular nic and the other one has a wireless card. Your XP is conncected to the hub with a network cable already, this is a hub and not a wireless router right??
Lets say cp1 is Win98 with a network card, cp2 is 98 with the wireless connection, and cp3 is xp with a network card.
cp 1 can connect to cp2 with a crossover cable (has to be a crossover cable and not the regular cables, make them a memeber of the same workgroup, assign cp1 an ip addy of say 192.168.0.4, subnet mask 255.255.255.0, cp2 192.168.0.3, same mask.
Windows 98 uses NetBIOS for name resolution so the two cps should be able to see each other, the only problem with using the crossover cable is that cp1 will only be able to see cp2 and never cp3. (Or at least, I have never been able to make it work :mad: )
If you want to connect all three together, I would just run a regular Cat 5 cable from each cp into the hub, replace the wireless card with a regular nic and run cables. The only thing on XP, in the properties of the connection, TCP/IP settings is to make sure that use NetBIOS over TCP/IP is selected. XP wants to use just DNS to resolve names to addys.
If this is a router, other steps will have to be taken and it might be easier to get another wireless card.
Hope this helps