I use the same wireless adapter on my laptop running Fedora 4 (for now). Unless something has changed recently, there isn't a native linux driver because the broadcom chip that it uses is less than a year old. I hope someone knows if there is anything different, but I'm fairly sure that's the case.
I'm not familiar with CentOS but I understand that fedora and centos are both based on Red Hat so they can't be so incredibly different. I was actually able to use the driver on the CD that came with the card. I'm assuming you have that CD, but if not I'm sure the driver you found is the same one I came across on the ndiswrapper page. To my knowledge the drivers are exactly the same.
Just so you know, I wasn't able to get this to work immediately and maybe my experience will help you. I installed this driver (from the CD and ndiswrapper page) with ndiswrapper about 4 times. Each time the install worked just fine, no errors that I can remember, but the card just would not work. I was able to sniff out something about this broadcom chipset not working well with a "regular" kernel and to enable symmetric multiprocessing.
I enabled SMP in my kernel, reinstalled the driver from the CD using ndiswrapper, and the card worked just fine. No problems with it at all.
Being that your laptop is old, I'm not sure if SMP is an option you want to enable. If it's already enabled for some reason then ignore my concern.
If it is a concern, however, maybe someone would be able to help.
But that's my story!
Good luck.
-Bill
