Have you try older version of Evox????and what's OS do you use on your PC??? if you using w/98 you probably neet Netbios to communicate with the Xbox...
and if you use older verison of Evox, when you go to setting ( NetworK) on your xbox not in static mode its should automatic assign you IP address in your xbox(but got to wait like 10-20 sec for its to show up), then just go to Network properties in your computer and change the last digit to something difference (work for me )
also if you using XP version, when you connect the cross over cable to your pc - xbox, the icon should appear like its connecting, if its appear to be red X than probably not software issue but hardware..