// Detect if browser is Netscape 3 + or IE 4 +.
bName = navigator.appName;
bVer = parseInt(navigator.appVersion);
    if ((bName == "Netscape" && bVer >= 3) || 
        (bName == "Microsoft Internet Explorer" && bVer >= 4)) br = "n3"; 
    else br = "n2";

// Create image objects, preload all active and inactive images.
    if (br == "n3") { 
    img1on = new Image();
    img1on.src = "images/btn1-over.jpg";
    img2on = new Image();
    img2on.src = "images/btn2-over.jpg";
    img3on = new Image();
    img3on.src = "images/btn3-over.jpg";
    img4on = new Image();
    img4on.src = "images/btn4-over.jpg";
    img5on = new Image();
    img5on.src = "images/btn5-over.jpg";
    img6on = new Image();
    img6on.src = "images/btn6-over.jpg";
    img7on = new Image();
    img7on.src = "images/btn7-over.jpg";
    
    img1off = new Image();
    img1off.src = "images/btn1.jpg";
    img2off = new Image();
    img2off.src = "images/btn2.jpg";
    img3off = new Image();
    img3off.src = "images/btn3.jpg";
    img4off = new Image();
    img4off.src = "images/btn4.jpg";
    img5off = new Image();
    img5off.src = "images/btn5.jpg";
    img6off = new Image();
    img6off.src = "images/btn6.jpg";
    img7off = new Image();
    img7off.src = "images/btn7.jpg";
    
  }

// Function to "activate" images.
function imgAct(imgName) {
    if (br == "n3") {
    document[imgName].src = eval(imgName + "on.src");
    }
}

// Function to "deactivate" images.
function imgInact(imgName) {
    if (br == "n3") {
    document[imgName].src = eval(imgName + "off.src");
    }
}