var imgHome = new Image();
imgHome.src = "images/btn_home.gif";
var imgHomeOver = new Image();
imgHomeOver.src = "images/btn_home_over.gif";

var imgAbout = new Image();
imgAbout.src = "images/btn_about.gif";
var imgAboutOver = new Image();
imgAboutOver.src = "images/btn_about_over.gif";

var imgProducts = new Image();
imgProducts.src = "images/btn_products.gif";
var imgProductsOver = new Image();
imgProductsOver.src = "images/btn_products_over.gif";