I need to install a new mouse. Don't know much about hardware installations. Do I have to remove/uninstall my old mouse, i.e. unplug it first? Or can I just unplug old mouse and plug new mouse in? Current mouse is Intellimouse Optical, new one is Intellimouse Explorer w/tilt wheel. Do I need to remove software from old mouse also? Should pc be off when I install/uninstall? I have Windows XP, HP pc.