// check to see if the entered value is an integer
function checkNum(thisInput){
	var thisValue = thisInput.value;
	//alert('checkin\' the fields!');
	var reNotADigit=/^\d+$/ //regular expression defining a string made up of digits!  yo!
	if (thisValue !='' && thisValue.search(reNotADigit)==-1){
		alert("You must enter a number in this field!")
		thisInput.value = '';
		thisInput.style.background = "#ffc";
		thisInput.focus();
		return false;
	}
	thisInput.style.background = "#fff";
	return true;
}