if (document.images)
{
preload_image = new Image();
img_path = new Array();

img_path[1] = "http://www.bristol-companies.com/img/design/nav/nav1.png";
img_path[2] = "http://www.bristol-companies.com/img/design/nav/nav2.png";
img_path[3] = "http://www.bristol-companies.com/img/design/nav/nav3.png";
img_path[4] = "http://www.bristol-companies.com/img/design/nav/nav4.png";
img_path[5] = "http://www.bristol-companies.com/img/design/nav/nav5.png";
img_path[6] = "http://www.bristol-companies.com/img/design/nav/nav6.png";
img_path[7] = "http://www.bristol-companies.com/img/design/nav/nav7.png";
img_path[8] = "http://www.bristol-companies.com/img/design/nav/nav0.png";

for(var i = 0; i<=img_path.length; i++)
preload_image.src = img_path[i];
}

function button_on ( imgId, imgRd )
{
    document.getElementById(imgId).src = "/img/design/nav/" + imgRd;

}

function button_off ( imgId )
{
  document.getElementById(imgId).src = "/img/design/nav/" + imgId + ".png";
}