I have a linksys WAG200G and it works very well for me, easiest place i would suggest is someplace like www.digitalplanet.co.za or have a look on www.jump.co.za to find a place that sells it.
The PPP Half Bridge is sometimes called DHCP Spoofing. This mode sets the X4 to present the Internet side IP address to a single computer that obtains this IP address via DHCP. The mode is relatively easy to configure, with just a couple of changes required from the standard NAT setting, and takes just a couple of minutes to complete.
The primary use of PPP Half Bridge mode is for applications that cannot be made to work with NAT. PPP Half Bridge mode is in fact the only way that the video and audio components of MSN Messenger will work on the X4, because of the lack of UPnP support.
Bizzare. Once in half-bridge mode, the first pc to do a dhcp request gets the isp assigned ip address, fine. And the rest of the machines plugged into the router ?