Hello,it seems it is still trying to connect to friends network.
Check firewall settings to see if it allows this connection on both main pc and your machine.
Make sure sharing is setup on main pc,as in share this connection with others on my network.
Run wirelss setup wizard.
Windows XP: Join a network
When trying to connect refresh networks list on the left hand side or try setup network listed there also.
To join the Vista network using an XP pc then the work groupe must be the same as Vista not XP.XP default is MSHOME.
Check the work groupe name make sure it is same on all pcs on the same network.