My apologies for giving too little info.
Using:
Mac Pro 2 x 2.8 GHz Quad-Core Intel Xeon
OS X 10.5.7
Ethernet Port 1 is fully working, for connecting to the internet, file sharing, screen sharing, etc.
Ethernet Port 2 is not working, for anything what-so-ever.
Thank you for taking the time to looking this through.