This is for testing purpose and it is about my home network. I highly recommend not to access networks you do are not allowed to. This could be illegal for some countries.
I have HP Pavilion dv6000 series (dv6699ea)
I use BackTrack distro live cd (http://distrowatch.com/table.php?distribution=backtrack)
I configured my wireless adsl modem 64 bit key.
After booting linux,
dv6699ea has ipw3945 wireless. You have to start wireless for this version:
cd /usr/src/drivers/ipw3945-1.2.0/ && ./load
aircrack support certain wireless cards please check it
Dump from wireless interface
bt ~ # airodump-ng eth1 --write test1
After collecting enough
bt ~ # aircrack-ng test1.ivs
It takes about less than a second to find keys for 64 bit.
So never use 64bit WEP wireless adsl modem.
I also tried
atheros based Dlink D520 in Fedora 6
and U.S. Robotics USB Adapter USR805422 in Windows XP. It worked.