Setspeed.exe is an old utility that has not had any updates since the PCI/PCI-x Ethernet controllers were the latest. The utility does not work with the newer Ethernet devices.
Besides using Windows device manager to set the speed and duplex, you have a couple of alternatives you could use. You could use WMI to set the speed and duplex, but a less complicated method would be to use the prosetcl.exeutility, which is installed on your hard drive when you install Intel(R) PROSet.
I have an example in another thread, Re: configure pro/1000 PT quad port for use on Hyper-v 2008 rc2, that deals with using prosetcl.exe to set speed and duplex.
I hope this helps you.