If xp,goto control panel/Wireless network setup wizard and follow the prompts.
This must be done on the host pc and you will need a flash drive or memory card and reader.
This will prompt you to insert the flash drive and then to the laptop and back again to the host pc.
This will have carried all the settings across for you.
Once done,check you have the security enabled,possibly the WEP or WPA encrypted key.
You may have to assign a new key.