Wireless problem sir i have dell latitude 520 laptop with xp os and i wan't to switch over to ubuntu but when i did so the wireless driver did'nt work further i don't know how to configure it so kindly help please reply me at coolsolid.aditya@gmail.com

I'm Guessing your using Ubuntu 7.04... Due to a bug in the native driver shipped with Ubuntu, the wireless card on this laptop is detected and installed but you cannot find any wireless networks. Here’s how to fix it.
* Let’s disable the native Ubuntu driver. Type this in a terminal:
gksu gedit /etc/modprobe.d/blacklist
and insert at the very end of the file:
# buggy broadcom wireless driver
blacklist bcm43xx
* Next, do this in a terminal:
sudo rmmod bcm43xx
* Now, let’s download and install the windows driver for the wireless card. You have to download it from the Dell support website. Click here to download it.
Or you can use the direct link to the executable:
http://ftp.us.dell.com/network/R140747.EXE
Since it’s a windows self-extracting executable, you need wine to use it:
sudo apt-get install wine
then:
wine <path_to_R140747.EXE>
Replace <path_to_R140747.EXE> with the actual physical path to the file you downloaded from the Dell support website. Follow the instructions and extract the files to a folder of your choice. Alternatively, you could extract the files on a windows machine and copy them over to your ubuntu system.
* Now, let’s install ndiswrapper. We need it to load the windows driver.
sudo aptitude install ndisgtk ndiswrapper-common ndiswrapper-utils-1.9
* Let’s install the windows driver:
sudo ndiswrapper -i <location_of_bcmwl5.inf_file>
Replace <location_of_bcmwl5.inf_file> with the path to the bcmwl5.inf file you extracted earlier.
* Let’s make sure the driver is installed:
sudo ndiswrapper -l
You should get something like this:
bcmwl5 : driver installed
device (14E4:4311) present (alternate driver: bcm43xx)
* Now we need to set up ndiswrapper to load our new driver automatically:
sudo gedit /etc/modules
and add a new line that says:
ndiswrapper
That’s it, restart your laptop. During the restart, the wiFI LED should light up. If it doesn’t, try the Fn + F2 key combination. After the reboot, configure your network settings:
System -> Administration -> Networking
Enable the wireless connection and tinker with the connection settings if you need to. You may have to disable the wired connection because wireless and wired connections may not work simultaneously - your mileage may vary in this regard.
Note:
It seems Network Manager prevents the card from connecting to detected wireless networks. I advise you to remove it if you can detect wireless networks but cannot connect to them. To do this, type the following in a terminal:
sudo apt-get –purge remove network-manager network-manager-gnome
Alternatively, you can open Synaptic and remove these two packages.
* Summary:
1.) Install ndiswrapper
sudo apt-get install ndisgtk ndiswrapper-common ndiswrapper-utils-1.9
2.) Install the windows wireless driver
sudo ndiswrapper -i <location_of_bcmwl5.inf_file>
Remember to replace <location_of_bcmwl5.inf_file> with the actual path to the location of the bcmwl5.inf file
3,) Make sure the card has been detected and installed
ndiswrapper -l
4.) Disable the native ubuntu wireless driver
gksu gedit /etc/modprobe.d/blacklist
Insert at the very end of the file:
# buggy broadcom wireless driver
blacklist bcm43xx
5.) Remove Network Manager if it gives you problems
sudo apt-get –purge remove network-manager network-manager-gnome
Reboot
You wireless card should be working flawlessly now.

I Hope this helps :)
Cheers
Jasonjohn89