<script>
function checkKey(event,nextField){
var pK = document.all? event.keyCode:event.which;
if(pK==13 && nextField) document.f.elements[nextField].focus();
return pK!=13;
}
</script>
<form name="f">
<input type="text" name="t1" onkeypress="return checkKey(event,'t2')">
<input type="text" name="t2" onkeypress="return checkKey(event,'t3')">
<input type="text" name="t3" onkeypress="return checkKey(event,null)">
</form>