Sorry its taken so long to update! I've just been looking at this problem again today, and called the phone company for some help. When they took off the encryption code I could connect to this network wirelessly on the computer that I have had problems with.
As soon as the encryption code is put back into place, the network is still there in my sharing center, still showing full amount of network strength, but when I try and connect it just says 'cannot connect to *network*'.
It seems like some issue with dealing with/accepting an security encryption code!!
It's a 9 digit long encryption code if that makes any difference? As I said, my macbook has no problems connecting.
It is a WPA-Personal security and a AES encryption type. Should I just be looking to switch the security type or encryption type?