Countermeasures

OK, so all this sounds pretty bad.  It looks like WEP hasn't met any of its security goals.  What should we do about it?
Just don't assume it's secure.
Treat your wireless network as a public network.
Put the wireless network outside your firewall.
In order for packets to cross from the wireless network to your intranet, they need to be authenticated with some other security mechanism
e.g. VPN, IPSec, ssh
Use whatever you use to allow your employees to log in from home, over the equally untrusted Internet

It isn't enough to use better 802.11 key management systems, since the problems aren't just with the keys!