var loadImgs = false;

function createImage( imgSrc ){
 var imgName = new Image();
 imgName.src = imgSrc;
 return imgName;
}

function changeImage( imgName, imgLoc )
{
 document[imgName].src = imgLoc ;
}

function loadImages()
{
 if (document.images)
 {
 start_off = createImage("images/over_sta.jpg");
 bio_on = createImage("images/over_bio.jpg");
 izb_on = createImage("images/over_izb.jpg");
 lmu_on = createImage("images/over_lmu.jpg");
 neu_on = createImage("images/over_neu.jpg");
 loadImgs = true;
 }
}