They can't harm each other with their powers. It will boil down to a fist fight of which Cyclops would win.
http://www.killermovies.com/forums/showthread.php?s=&threadid=390221&highlight=Havok+cyclops
http://www.killermovies.com/forums/showthread.php?s=&threadid=316778&highlight=Havok+cyclops
http://www.killermovies.com/forums/showthread.php?s=&threadid=331685&highlight=Havok+cyclops