Sounds like if its working on the network cable and not wifi then your machine is not being leased an ip address for wireless to get on the network from the router. could be many things…
Drop the network cable into the xp machine.
click the windows 'start' button then the 'run' option on the start menu and type in the run dialog box:
ipconfig
hit return on the keyboard.
you should see an ip address. something like:
ip address………:192.168.1.2
or similar.
whatever it is listed as type this into internet explorer and hit return (as if it was a web site – but without the http://). you should then get a username and password box. Usually username is:
admin
password is:
whatever you have set it as or the default one in the manual.
from here it should take you to the wizard for the router. set up WPA encryption. Better way to go than the CD.
Then once done double click on the wireless icons on the bottom right toolbar and view wireless networks and connect with your new encrypted password setup in the wizard.
also make sure wireless is not turned off on the laptops (a switch or sometimes a button. easily done)