ipw3945d and therefore iwl3945d is not used anymore. I have the same wifi card in my Lenovo. With the new driver the card registers as wlan0.
You also need to have the latest firmware. Look in /lib/firmware and see if the file iwlwifi-3945-1.ucode is there. If
it isn't, google for it and you will be able to get it from Intel. Things should start working then.
That pup is harder to find than I remembered. Get the file here...http://www.intellinuxwireless.org/?n=downloads&f=ucodes_3945
get version iwlwifi-3945-ucode-220.127.116.11.tgz