It is a bit tricky (took me almost two days :), but basically this is the procedure:

- configure your wireless card
(using ndiswrapper is described in another article)
in case your wifi card is identified as wlan0 add the following to /etc/network/interfaces

auto wlan0
iface wlan0 inet dhcp
pre-up wpa_supplicant -Bw -Dwext -iwlan0 -c/etc/wpa_supplicant.conf
post-down killall -q wpa_supplicant


- install and configure wpasupplicant
# apt-get install wpasupplicant

create /etc/wpa_supplicant.conf with simular content

network={
ssid="testwlan"
psk="7cHBV294H_something_long_and complicate"
scan_ssid=1
key_mgmt=WPA-PSK
proto=WPA
pairwise=CCMP TKIP
group=CCMP TKIP
}


This would automatically engage/shutdown wpasupplicant on up/down of the wlan0 interface.
Works nice for me :)