Unable to Connect to Internet through Wi-Fi

I have just formatted my Inspiron 640M laptop and installed Windows Xp.I have installed all the drivers properly from Dell Website. Even, When i check windows device manager, no errors or missing drivers are displayed. When i open Intel PRO/Set Wireless Utility my network name is displayed. When i click on displayed network name and try to enter the Netwrok Key i was not able to connect to Internet.

Can anyone help me to get over this problem. Any help would be much appreciated.

By the way, the wireless Netword card available in my system is 'INTEL NEXT-GEN WIRELESS-N MINI-CARD', i have downloaded all the drivers from Dell's website using my service tag