To rule out a hardware issue download Fatdog64. Fatdog64-702.iso Burn the iso file to a CD by right clicking on a Windows 7 computer and selecting Burn Disk Image or by using a program like Imgburn to burn an image to disk. Boot the disk and see if you can connect via Ethernet or Wireless.
If a CD is not available then you can use Rufus with the iso to create a bootable USB flash drive. Attach a flash drive to your available computer. Run Rufus and select MBR with BIOS or UEFI for a partition scheme. Leave all boxes as checked. Where you see FreeDos in the dropdown box select iso image. click the small icon and browse to the iso file of Fatdog. Press Start. Backup any data on the flash drive as it will be erased.
Attach the flash drive and boot the computer. Tap Esc while booting then F9, This should bring up a boot menu where you can select your boot device.
This is XP SP3, correct?
If Fatdog cannot connect via Ethernet or USB then you are dealing with a possible motherboard problem. Googling this particular model shows that the problem is common. A possible solution would be to use a USB WIFI dongle like this. There are cheaper generic ones on Ebay.