function addEngine(which){
	switch (which){
		case 1:
			window.sidebar.addSearchEngine(
			  "http://download.polymeta.com/toolbar/scienceroll.com.xml",
			  "http://download.polymeta.com/toolbar/scienceroll.com.gif",
			  "ScienceRoll",
			  "General" );
			break;
		case 2:
			window.external.AddSearchProvider("http://download.polymeta.com/toolbar/scienceroll.com.xml");
			break;
		default:
			break;
	}
}