I had the same problems... make an EvoX boot disc with the follow configured EvoX settings:
Make your default gateway and subnet mask the EXACT same as your pc's, set your Xbox I.P to 192.168.0.3. To find your Pc's subnet/defaultgateway go to Start->All programs-> accessories-> command prompt-> then type ipconfig (that's for winxp) for win2k i think its the same, and for 98/95:
start->run->winipcfg