I'm no Linux guru, but this sounds to me like a driver problem. If I were in your place, I'd first get the Windows drivers for the card from the Broadcom site. Then, I'd get a copy of Linuxant's excellent Driverloader software (less than $20 at www.linuxant.com)
. This combination did the job for me with SuSE and a Broadcom wireless card. Driverloader is designed to handle problems such as these.
(I'm a huge proponent of open source software, and Driverloader is one of a very few commercial products I ever recommend in a Linux environnment.)