According to the Fujitsu site the drivers for your NIC are embedded in XP.
If this is the case then it could be that there is a problem with the card ( it is actually a chip ) itself.
The drivers needed are Realtek RTL8139 and it is this that should be showing in Device Manager.
Go back to Network Adapters in Device Manager ( devmgmt.msc ) right click on each of the devices with a yellow exclamation mark > uninstall.
Re-boot the machine.
Windows should locate new hardware and, if the drivers are embedded, should auto install them.
If not then the drivers are here:
click here
Windows XP > click on US1 or US2