I have just resolved a problem when using the D-Link DSL-300T in conjunction with a WRT45G and I thought I'd share the solution to avoid much hair pulling. When I plugged the two units together, it worked straight away, but every 20 seconds or so, the connection would drop for a few seconds which made the setup unusable. It seems that out of the box, the two units are using the same subnet range for their DHCP servers (192.168.1.x) which is leading to conflicts. The solution is quite straightforward, you need to change the IP address of the WRT54G to something else, like 10.1.1.1 using its web interface, this will also cause its DHCP server to serve addresses to your LAN computers in the 10.1.1.1xx range. Enjoy !