I've pasted the link to the driver below.
Note that it's a Dell .exe file. It is what is called a self extracting executable. Som of those including Dells can be extracted in Linux using a command in the form of:
unzip -a <dell driver name> -d /driver
The extracted files will be located in the 'driver' directory directly off the directory you have the exe stored in.
There will be several sets of the files you need. You'll see sub-directories labelled US, Europe, ROW etc. Choose your location. What you really need are the files 'bcmwl5.inf' and 'bcmwl5.sys' for your location.
I can't remember now what else is in the extracted data but avoid any bcmwl6 driver files. They are for Vista and ndiswrapper doesn't work with Vista files.
Post back with any problems or questions.