Welcome to LQ!
And welcome to the wild, wooly world of Broadcom wireless. The basic problem is that the Linux kernel has an open-source driver (called b43) but no Linux distro can supply the firmware needed for the card to actually function (Broadcom licensing prohibits it). The upshot is that the card looks like it should function, but doesn't actually. So, you need to install firmware before it will actually work. If you check out these instructions
, I suspect that something similar to the Fedora instructions should work on CentOS>