function imgOn(imgName) {
	if (document.images) {
//	   alert(eval(imgName + "on.src"));
		document[imgName].src = eval(imgName + "on.src");        
	}	
}

function imgOff(imgName) {
	if (document.images) { 
		document[imgName].src = eval(imgName + "off.src");        
	}	
}

if (document.images) {
	imgNav1on = new Image();
	imgNav1on.src = "images/nav/home_over.jpg";
	imgNav2on = new Image();
	imgNav2on.src = "images/nav/about_over.jpg";
	imgNav3on = new Image();
	imgNav3on.src = "images/nav/toptips_over.jpg";
	imgNav4on = new Image();
	imgNav4on.src = "images/nav/upload_over.jpg";
	
	imgNav1off = new Image();
	imgNav1off.src = "images/nav/home.jpg";
	imgNav2off = new Image();
	imgNav2off.src = "images/nav/about.jpg";
	imgNav3off = new Image();
	imgNav3off.src = "images/nav/toptips.jpg";
	imgNav4off = new Image();
	imgNav4off.src = "images/nav/upload.jpg";
}