You say you have tried Winsockfix so that covers that area.
Also say you have run ipconfig/release.....what showed up?
Did it show the usual IP assigned to the ethernet.
Is the ethernet DHCP'd and when you run ipconfig/release with the ethernet cable unplugged does it behave proper on unplug? (ie. IP goes to 0.0.0.0.)
Have you also tried deleting the Local Area Connection and renewing the network connection....
Please also run through these TCP/IP stack repair options for XP with SP2.
Open a cmmd prompt with admin priv's again
Reset WINSOCK entries to installation defaults by running: netsh winsock reset catalog
Reset TCP/IP stack to installation defaults: netsh int ip reset reset.log
Reboot the machine.