function getAppVersion() {
        appstr = navigator.userAgent;
        if( (appstr.substring(0, 11) == "Mozilla/3.0") )
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/4.0")
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/4.5")
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/4.6")
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/4.7")
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/5.0")
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/6.0")
                return 1;
        if (appstr.substring(0, 11) == "Mozilla/6.2")
                return 1;
        return 0;
}

function swtch(num, imgname) {
        if (getAppVersion())
                imgname.src = img[num].src;
}

imgsrc = new Array();
imgsrc[0] = "images/menu.jpg";
imgsrc[1] = "images/mn_book.jpg";
imgsrc[2] = "images/mn_author.jpg";
imgsrc[3] = "images/mn_excerpts.jpg";
imgsrc[4] = "images/mn_reviews.jpg";
imgsrc[5] = "images/mn_purchase.jpg";
imgsrc[6] = "images/mn_home.jpg";


if (getAppVersion()) {
        img = new Array();
        for (i = 0; i < imgsrc.length; i++) {
                img[i] = new Image();
                img[i].src = imgsrc[i];
        }
}