bcm43xx _or_ ndiswrapper - pick one, you cannot use both.
If you want to use ndiswrapper - add bcm43xx to /etc/modprobe.d/blacklist
If you want to use bcm43xx - You will need to get hold of firmware for the card (read
here for more), then run 'ifconfig <wireless interface> up' to load the firmware and activate the card before scanning.