on your laptop that is connected ok click on the link below
http://192.168.1.1
This should take you to the login page for your router, login with the following
username: admin
Password: password
once logged in look on the left hand side for the link to wireless setting and click on it
towards the bottom of this page you will see your network key, make a not of this.
Now go to the PC and open your wireless network list, disconnect from the wireless network and then reconnect, when it asks for the key put in the one you have made a note of and click connect.