If you get the compilation error Unknown symbol: wireless_send_event you will need to enable the CONFIG_NET_RADIO option and recompile your kernel or find a kernel with this option already enabled. Checking for the /proc/net/wireless file is not a good way of making sure you have this option enabled since it will exist if one or both of CONFIG_NET_RADIO and CONFIG_NET_PCMCIA_RADIO options are enabled.

da http://ndiswrapper.sourceforge.net/m.../index.php/FAQ

controlla di avere inserito nel kernel e caricato i moduli per le usb