Unless something has changed with 10.3 regarding Broadcomm wireless card support, I think you will have to do as andy mentioned, use the ndiswrapper tutorial. I installed 10.2 on my friend's Dell with the same card that you have, and to get wireless working I had to use ndiswrapper. I do not have experience with the fw cutter, so I stuck to what I knew. The ndiswrapper route is easy to follow, and worked first time for me. Once you do that, Knetwork manager-assuming you use it-will show you available networks.