//image cache

//image on
nav1on = new Image();	nav1on.src = "../images/nav/nav1b.gif";
nav2on = new Image();	nav2on.src = "../images/nav/nav2b.gif";
nav3on = new Image();	nav3on.src = "../images/nav/nav3b.gif";

//image off
nav1off = new Image();	nav1off.src = "../images/nav/nav1a.gif";
nav2off = new Image();	nav2off.src = "../images/nav/nav2a.gif";
nav3off = new Image();	nav3off.src = "../images/nav/nav3a.gif";