//global variables that can be used by ALL the function son this page.
	var inputs;
	var imgFalse = '/images/checkbox_no.jpg';
	var imgTrue = '/images/checkbox_yes.jpg';

	//this function runs when the page is loaded, put all your other onload stuff in here too.
	function init() {
		replaceChecks();
	}

	function replaceChecks() {
		
		//get all the input fields on the page
		inputs = document.getElementsByTagName('input');

		//cycle trough the input fields
		for(var i=0; i<inputs.length; i++) {

			//check if the input is a checkbox
			if(inputs[i].getAttribute('type') == 'checkbox') {
				
				//create a new image
				var img = document.createElement('img');
				
				//check if the checkbox is checked
				if(inputs[i].checked) {
					img.src = imgTrue;
				} else {
					img.src = imgFalse;
				}

				//set image ID and onclick action
				img.id = 'checkImage'+i;
				//set image
				img.onclick = new Function('checkChange('+i+')');
				//place image in front of the checkbox
				inputs[i].parentNode.insertBefore(img, inputs[i]);
				
				//hide the checkbox
				inputs[i].style.display='none';
			}
		}
	}

	//change the checkbox status and the replacement image
	function checkChange(i) {

		if(inputs[i].checked) {
			inputs[i].checked = '';
			document.getElementById('checkImage'+i).src=imgFalse;
		} else {
			inputs[i].checked = 'checked';
			document.getElementById('checkImage'+i).src=imgTrue;
		}
	}

	window.onload = init;