I'm going to chime in here to say this is a bad thing to do unless you are recieving problems like the emplode error. Windows can usually figure out all those setting on it's own, and setting the wrong thing can have nasty effects on not only your system, but any other system on the same network as your system.

(I was forcing a duplex setting on my Linux server in the house once, and ended up making my new 100mbps network slower then the old 10)