Failed to integrate with Intel 3945ABG Wireless card

I have Desktop computer with integrated Intel 3945 mini-card wireless. I have Default install OS of Vista Beta 2, Ultimate Ed., for running any other application i found no problem. when i boot up my system, wireless light comes on and connects with default wireless network which provides an indication that it works fine. After a short period of time, I notice I have lost network connectivity. The Network Center still shows connected with Excellent signal strength, but the wireless radio LED on my computer goes off.
Later on I tried several times by making connecting and disconnecting the Network but the same issue remains.

Thanks for your suggestions.

Each new OS has the problem of early Dell driver support. Looking at your problem I suspect your issue is a driver problem.you can check for the driver details which will suggest you that there are no BETA drivers yet.
http://www.intel.com/support/wireles.../cs-020936.htm

You may found the drivers from the following link:
http://www.intel.com/support/wireles.../cs-010623.htm

check if you find the driver for your system then you would be lucky otherwise..

The latest generic drivers can be installed on 5472 with a bit of tweaking :-

1. Run the self extracting installer. It will fail but extract the files to c:\intel\...
2. Edit the .inf file (it's a very simple inf) so that the Vista line points at the XP installer
3. Navigate to the installer. Right click and run in compatibility mode for XP + as Administrator.
4. Run the installer (or optionally run the other installer from within the XP folder that the .inf points to.
5. It might throw up an error toward the end of the install. Ignore the error box until the install has finished, then close the error box.
6. Reboot and enjoy your new drivers.

They work very well for me.