I was called to set up a customer's PC to talk to an Orange Livebox router. I had great problems with the PC's wireless adaptor failing to connect to the network until people put me straight on a couple of peculiarities of this router. I thought I'd share them with you in case you fall foul of them.
Firstly, although the config menus don't make any mention of MAC address filtering, the Livebox does actually seem to filter on MAC address: it refuses to talk to a MAC that it doesn't know about. The trick is to put the router into "pairing mode" which allows it temporarily to accept connections from any device and to learn those MAC addresses for future use. To do this, press the "1" button on the side of the router. This wireless light will flash at a rate of about once per second. Now get the PC to connect. You have 10 minutes to do this. Once you've connected, you will continue to have access even after the router has come out of pairing mode.
Secondly, the Livebox seems to support simultaneous WEP and WPA encryption. I found that PCs which use the Windows XP Zero Config Service fail to get an IP address whereas ones which use proprietary software are OK. This is resolved by setting the Livebox's encryption to "WPA only" rather than "WPA and WEP".
Hope these hints help you avoid tearing your hair out like I was!
By the way, if you have a lot of PCs to connect wirelessly, you might decide to change the WPA key (which Livebox calls a WEP key) to something a bit easier to type than the long string of hex digits that is the default key!