if (document.images){

nav1 = new Image; nav1a = new Image;
nav2 = new Image; nav2a = new Image;
nav3 = new Image; nav3a = new Image;
nav4 = new Image; nav4a = new Image;
nav5 = new Image; nav5a = new Image;
nav6 = new Image; nav6a = new Image;

nav1.src = "gfx/nav1.gif"; nav1a.src = "gfx/nav1a.gif";
nav2.src = "gfx/nav2.gif"; nav2a.src = "gfx/nav2a.gif";
nav3.src = "gfx/nav3.gif"; nav3a.src = "gfx/nav3a.gif";
nav4.src = "gfx/nav4.gif"; nav4a.src = "gfx/nav4a.gif";
nav5.src = "gfx/nav5.gif"; nav5a.src = "gfx/nav5a.gif";
nav6.src = "gfx/nav6.gif"; nav6a.src = "gfx/nav6a.gif";
}

function chgImg(imgField,newImg) {
		if (document.images) {
			document[imgField].src= eval(newImg + ".src")
		}
}