I first encountered this problem with my onboard nforce lan. I ran GC Sim and couldnt select ANY of the 4 options (100mbps full, half, ect...). So I went out and bought a brand new Linksys nic, and im having the same problems! I got the latest drivers for the Linkysys from the net, and its set to 'auto sense' in my device manager. Any idea why GC Sim isnt working?