var image1 = new Image();
image1.src = "support/nb-products-on.gif";
var image2 = new Image();
image2.src = "support/nb-new-on.gif";
var image3 = new Image();
image3.src = "support/nb-quote-on.gif";
var image4 = new Image();
image4.src = "support/nb-eng-on.gif";
var image5 = new Image();
image5.src = "support/nb-about-on.gif";
var image6 = new Image();
image6.src = "support/nb-contact-on.gif";

function chgButton(oImg, nImgType){
    var sSrc = oImg.src;
    var nPos = sSrc.lastIndexOf("-");
    var sImgType;
    if (nImgType == 1){
        sImgType = ".gif";
    } else{
        sImgType = ".jpg";
    }
    
    if (nPos > 0){
        var sImgSuffix = sSrc.substr(nPos, sSrc.length);
        var sSrcBase = sSrc.substr(0, nPos);
        if (sImgSuffix == "-off" + sImgType){
            oImg.src = sSrcBase + "-on" + sImgType;
            return(true);
        }else if (sImgSuffix == "-on" + sImgType) {
            oImg.src = sSrcBase + "-off" + sImgType;
            return(true);
        }
    }
}