Solved. I took the back plate off and it was visible that the White wire was not connected as it should be. Once attached my laptop works fine.
I received a new Dell XPS laptop literally an hour ago and have been having consistent connection issues with it. As it stands I have a Wi-Fi network that has been in place and operating perfectly with a main computer (plugged into the network), two Dell inspiron laptops, an iPod touch, an X-box and a Lenovo laptop all connected wirelessly to the network. They have all worked fine and are able to connect perfectly to the internet with all bars filled in. All these devices have been able to connect flawlessly across my house on different levels to the router and even outside. When I took out this new laptop, downstairs and quite far away from the router but well within the usable range of the other computers and devices, it failed to connect or even detect our home network. So far I have only been able to connect it, and even then only 1-3 bars of reception, when it is sitting on the desk next to the Wi-Fi router, if I move it more than a yard/metre away it disconnects. I have tried restarting the modem which hasn't worked and have tried using the F2 button to turn off and then on the computer's side of the reception with no luck.   What can I do to get it connecting like the others?        
Wi-Fi connection issues with new computer