function roll(theimage,mode,imgfile,imgext){
	if(mode == 1){
		theimage.src = 'images/' + imgfile + '_on.' + imgext;
	}
	else{
		theimage.src = 'images/' + imgfile + '_off.' + imgext;
	}

}

//;" onmouseout="roll(this,0,'topnav_firm','jpg');"