Can your Brothers PC see the other PC?
Can it connect to the net?
What is the IP address of both PC's? It should read 192.168.0.1 and the other 192.168.0.2
Try pinging each PC and see what the results are.
Also if you have XP in the run box type CMD then in the dos looking screen type ipconfig /all (note the space between the G and /) Do that on both PC's you should see the IP addresses as stated above if not then try the network wizard again.