var theImages = new Array();
theImages[0] = 'HeaderGraphic_Fittings.gif'
theImages[1] = 'HeaderGraphic_Valves.gif'
theImages[2] = 'HeaderGraphic_TOLCO.gif'
theImages[3] = 'HeaderGraphic_Chemtrol.gif'
function showImage(baseUrl){
    var p = theImages.length;
    var preBuffer = new Array()
    for (i = 0; i < p; i++){
       preBuffer[i] = new Image()
       preBuffer[i].src = theImages[i]
    }
    var whichImage = Math.round(Math.random()*(p-1));
    if (baseUrl != null && baseUrl != "" && typeof baseUrl != undefined) {
        baseUrl = baseUrl + "/";
    } else {
        baseUrl = "";
    }
        
    document.write('<img src="'+baseUrl+theImages[whichImage]+'" border="0" >');
}