nav_off = new Image();
nav_off.src = "/Cancer/Images/Navigation/Nav_Off.jpg";

nav_home = new Image();
nav_home.src = "/Cancer/Images/Navigation/Nav_Home.jpg";

nav_about = new Image();
nav_about.src = "/Cancer/Images/Navigation/Nav_About.jpg";

nav_care = new Image();
nav_care.src = "/Cancer/Images/Navigation/Nav_Care.jpg";

nav_tour = new Image();
nav_tour.src = "/Cancer/Images/Navigation/Nav_Tour.jpg";

function Switch(navImageId, newImage)
{
    document.getElementById(navImageId).src = newImage.src;
}