function swapImg(imgName,imgSrc) {
	document.images[imgName].src = imgSrc;
} 
// <A HREF="" 
// onMouseOver="swapImg('button','images/button_over.gif')" 
// onMouseDown="swapImg('button','images/button_down.gif')" 
// onMouseOver="swapImg('button','images/button_over.gif')" 
// onMouseOut ="swapImg('button','images/button_default.gif')"><IMG NAME="button" SRC="images/button_default.gif" BORDER=0></A>