On my son's PC I recently reinstalled Windows XP SP2 and connected it to the internet using an Asus WL-167 Wireless Adapter. After a few days it stopped working and the message showing in the bottom right hand corner of the screen was "Acquiring Network Address" yet this message appeared constantly, even if the PC was left on for many hours.
Having done some research online it appeared that it was an error with the settings on the Asus WL-167 wireless adapter and the encryption method being used to connect to the wireless router. I realised that when I initially connected the Asus WL-167 Wireless Adapter the PC was running Windows XP Service Pack 2 but that then updated to Service Pack 3 shortly afterwards and the Asus WL-167 Wireless Adapter stopped working giving the error Acquiring Network Address constantly.
To fix the Acquiring Network Address problem the solution was as follows:
1) Open 'Network Connections' (accessible from the Control Panel).
2) Right click on the Wireless Connection, and select 'Properties'.
3) Select the 'Wireless Networks' tab.
4) Under the 'Preferred networks' section, click on your network and click 'Properties'.
5) Under the 'Association' tab, there is a drop down menu specifying 'Network Authentication'. This should be set to WPA. Set Data Encryption to TKIP.
Having done this and re-entered my WEP key the PC was then able to connect to the router and internet.
It would appear that this Acquiring Network Address error can be caused by the Windows Update from XP SP2 to Service Pack 3 and that some wireless setting is reset as part of the Windows update in SP3. So if your PC is unable to connect to wireless network after installing Windows XP SP Service Pack 3 then the above information may be a solution to resolve the problem.