hi chap, very strange, first thing i'd do is check device manager to ensure that both cards are installed and enabled.
Also, I know that my Dell disables all networking by default when on battery, are you running on the mains?
Have you got any other machines in the house? If so, are they connected OK?
If you need help with any of the above, reply and I/We can talk you through it. (unless anyone has any other ideas?)