I was reading your thread by accident and i had the same problem with my PCMCIA wireless network card. Well as it seems ubuntu does not handle the wireless network properly when you use ndiswrapper for your drivers.

Also, you may have noticed that as soon as you modprobe ndiswrapper into your system, it becomes unstable or unresponsive or you get a "sticky" keyboard. But when you connect to a network everything is working fine again.

You may find that even you have set up everything right you still cant connect to your wireless network. If this happens goto :

System --> Administration --> Netoworking --> Find your wireless network card --> Properties --> UNtick "This device is configured" --> ok --> ok
then repeat the process and TICK the option, --> ok --> ok and run
#==> ifup wlan0 (or whatever your wNIC is) again It will work.