//declare array
    var navImageArray = new Array('custom_tops','custom_racks','electronics','testimonials','contact');
    var imagePath = 'images/';
    var rolloverImages = new Array();
    var outImages = new Array();
    preloadNavImages();

    function preloadNavImages() {
        for(loop=0;loop<navImageArray.length;loop++)
        {
            var an_image = new Image();
            rolloverImages[loop] = imagePath + "but_" + navImageArray[loop] + "_ro.gif";
            outImages[loop] = imagePath + "but_" + navImageArray[loop] + ".gif";
            an_image.src = rolloverImages[loop];
            var an_image2 = new Image();
            an_image2.src = outImages[loop];
        }
    }

    //mouse over
    function over(pos){
        var tabImage = eval("document."+navImageArray[pos]);
        tabImage.src = rolloverImages[pos];
    }

    //mouse out
    function out(pos) {
        var tabImage = eval("document."+navImageArray[pos]);
        tabImage.src = outImages[pos];
    }