Not an expert but have networked a PC and my Mac through a router to ADSL.
Settings that work for me are as follows:
System Prefs/Network/TCP/IP: Configure IPv4: Using DHCP
System Prefs/Network/PPoE: Deselcted (using PPoA)
System Prefs/Network/Ethernet: Configure: Automatically
Just make sure you have created a 'Location' and have the network port configurations set to 'on'.
Use the 'Network Utility' (Should be in Applications/Utilities) to check all the ports and comms. 'Terminal' in same directory should let you telnet into Unix core.
Hope I'm not telling you how to suck eggs.
