A week or so back I posted about my new laptop and a networking issue when setting it up.
Apparently other people have had the same problem as I did and not found a solution, so here is how to work around it.
Windows will quite happily see the WEP encrypted wireless network and will claim to have joined correctly, but it will not pick up a DHCP address, and if configured with a static address will fail to see the rest of the network.
Temporarily disable any encryption on the wireless network, this will allow the laptop to join the network quite happily, you can then re-enable WEP and MAC address filtering as appropriate and everything will continue to work correctly.
I’ve no real idea what causes the problem, I only worked it out after 20 minutes of fiddling when I noticed that my new laptop would connect to my neighbours unencrypted AP quite happily, but wouldn’t work properly with my WEP enabled AP. I had the same problem with both the builtin Intel 2200BG adapter, and a PRISM based Netgear WG511 card from my old laptop.