First ensure Non Wireless is working.
Go into YAST Network devices Network card
Disable the User Controlled with Network Manager. (Chose Traditional method with ifup).
Change settings also to start up MANUALLY.
Change also the default RUN level to 3 in SYSTEM services runlevel
(that way you get a login prompt before the X server starts -- it's always better IMO to be able to see the console at system start up so you can quickly see if there are any problems.).
Exit YAST and type on a console as root INIT 3.
This should drop you out of the X server. Logout and LOGIN as ROOT.
Now type IFUP eth0. when it's up just try something like ping
www.google.co.uk. If you still get unknown host type ifdown eth0 then ifup eth0 again and try pinging again.
If this still fails reboot. At the login prompt type ifup eth0 as root. Should work now.
To start the X server just type STARTX
If you still can't get internet access then your DVD might be one of those "funny magazine one's" which sometimes give inexplicable problems.
I find the older IFUP method better than the newer Network manager method.
Now Wireless is a totally different manner -- without knowing the card or type it's almost impossible to diagnose problems - look in the Wireless networking section on the forum.
Cheers
-K