//preload images
		if (document.images) {
			
			btnHome = new Image();
			btnHome.src = "images/btnHome.gif";
		  btnHomeHover = new Image();
			btnHomeHover.src = "images/btnHomeAlt.gif";
				
			btnAbout = new Image();
			btnAbout.src = "images/btnAbout.gif";
			btnAboutHover = new Image();
			btnAboutHover.src = "images/btnAboutAlt.gif";
			
			btnPictures = new Image();
			btnPictures.src = "images/btnPictures.gif";
			btnPicturesHover = new Image();
			btnPicturesHover.src = "images/btnPicturesAlt.gif";
			
			btnContact = new Image();
			btnContact.src = "images/btnContact.gif";
			btnContactHover = new Image();
			btnContactHover.src = "images/btnContactAlt.gif";
			
			}