Dell Inspiron 1501

I have got Dell Inspiron 1501 Laptop with Windows Vista Home Basic Edition licensed version. One day the problem arises in its wireless network card. I have gone through the following steps to diagnose the actual problem. Let me explain the problem first.
The wireless network card did not detected and connected with surrounding available network. I was trying to connect to the D-Link wireless router to access Internet. First of all I restarted the laptop and observed its connection but no avail. Then I checked its status in the bios setup program whether it is ON or OFF. But apparently it appeared as ON status. Now I again rebooted the machine to verify it with the keys Fn + F2 (OFF and then ON ) and it showed the green light when I had pressed the keys again to turned it back to ON. Now this represents the hardware part of network adapter was working fine. I got the idea to replace the device drivers with new version which was available on the dell site. I have downloaded the latest drivers and installed them into the laptop. Surprisingly , the hardware is reinitialized as I thought and its seemed the activity of the network appeared in the corner of the desktop and connected.
Next day when I again open my notebook and found that it could not detect the network by the wireless device. Then I tried to contact to the dell support but failed to do so. I also tried to find the solution from different forums but did not get any solution of this problem. At last, I thought that there might be some problem with the operating system.
But due to shortage of time , I am going to buy a new external Belkin network card available in the market. If somebody have gone through the same problem and want to share his experience please write it here.
Thanks.

Faisal.