My laptop was originally installed with Windows XP SP3, however the speed is really slow. I installed Ubuntu 9.04 on my Dell D420 with a WWAN 5520 Card. This really gives slow laptop a chance for reborn.
The most impressive thing is mobile broadband support. Right on the first boot after installation, the network editor asked for a few questions.
Within some points and clicks, I am connected with the 3.5G network!