intel pro wireless 3945ABG + Feisty Ubuntu

[I. <iterazione gmail com>]

Hello friends,
i've just installed on my laptop Ubuntu Feisty (last version):
i have a intel pro wireless 3945ABG, which ubuntu seems to
detect and activate. Infact, on the Network Manager, i can
see the list of wireless networks in my neighborhood. But
when i try to connect, it asks for WEP key and when i type
it ... it doesnt connect. Also when i try to connect to a free
network (there is one here), it does not go on.
So the problem is that my box notices networks, but can't
connect them....

Seems like it does not give me an ip address.

What should i do, in your opinion?
Someone has this configuration  (feisty+intel pro wireless 3945abg) ?
 
THANKS for your help guys... :-)


Regards,
Jack