if (document.images) 
{
img1 = new Image();
img2 = new Image();
img3 = new Image();
img4 = new Image();
img1.src = "images/colinall.jpg"
img2.src = "images/colinall2.jpg"
img3.src = "images/colinall3.jpg"
img4.src = "images/colinall4.jpg"
}