Found my notes...

I've done a bit of exploration on a Dell Latitude D810, with a Broadcomm BCM4309
rev3. Not quite the same as yours, but close. I'm keeping it WinXP-only for
now, (small HDD), but I've tried some live CDs.

I've never gotten Wi-Fi to work on this machine with any *buntu, even with the
procedure I posted before (which claims it should work without a reboot).

However: Wi-Fi "just worked" when I booted a Fedora 15 Live CD. All I had to do
was enter my WPA key.

You might want to try a different lightweight distro.