MCB,
Вариант ...
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
function checkAll(oForm,checked)
{
oForm['checkbox[1]'].checked = checked;
oForm['checkbox[2]'].checked = checked;
oForm['checkbox[3]'].checked = checked;
}
</script>
</head>
<body>
<form name="form1" method="post" action="">
<input type="checkbox" name="total" value="checkbox" onClick="checkAll(this.form,this.checked)">Отметить все
<input type="checkbox" name="checkbox[1]" >1
<input type="checkbox" name="checkbox[2]" >2
<input type="checkbox" name="checkbox[3]" >3
</form>
</body>
</html>