if (document.images) {

nav_home_on = new Image();
nav_home_on.src = "images/nav_home_on.gif";
nav_home_off = new Image();
nav_home_off.src = "images/nav_home_off.gif";

nav_projects_on = new Image();
nav_projects_on.src = "images/nav_projects_on.gif";
nav_projects_off = new Image();
nav_projects_off.src = "images/nav_projects_off.gif";

nav_about_on = new Image();
nav_about_on.src = "images/nav_about_on.gif";
nav_about_off = new Image();
nav_about_off.src = "images/nav_about_off.gif";

nav_contact_on = new Image();
nav_contact_on.src = "images/nav_contact_on.gif";
nav_contact_off = new Image();
nav_contact_off.src = "images/nav_contact_off.gif";

tpleft_on = new Image();
tpleft_on.src = "images/tpleft_on.jpg";
tpleft_off = new Image();
tpleft_off.src = "images/tpleft_off.jpg";

tpright_on = new Image();
tpright_on.src = "images/tpright_on.jpg";
tpright_off = new Image();
tpright_off.src = "images/tpright_off.jpg";

btmleft_on = new Image();
btmleft_on.src = "images/btmleft_on.jpg";
btmleft_off = new Image();
btmleft_off.src = "images/btmleft_off.jpg";

btmright_on = new Image();
btmright_on.src = "images/btmright_on.jpg";
btmright_off = new Image();
btmright_off.src = "images/btmright_off.jpg";


}
function turnOn(imgName) {
        if (document.images) {
        	document[imgName].src = eval(imgName + "_on.src");
        }
}
function turnOff(imgName) {
        if (document.images) {
        	document[imgName].src = eval(imgName + "_off.src");
        }
}