function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		TBCtechMenu_01_over = newImage("images/TBCtechMenu_01-over.gif");
		TBCtechMenu_02_TBCtechMenu_01_over = newImage("images/TBCtechMenu_02-TBCtechMenu_.gif");
		TBCtechMenu_03_over = newImage("images/TBCtechMenu_03-over.gif");
		TBCtechMenu_04_over = newImage("images/TBCtechMenu_04-over.gif");
		TBCtechMenu_05_over = newImage("images/TBCtechMenu_05-over.gif");
		TBCtechMenu_06_over = newImage("images/TBCtechMenu_06-over.gif");
		TBCtechMenu_07_over = newImage("images/TBCtechMenu_07-over.gif");
		TBCtechMenu_08_over = newImage("images/TBCtechMenu_08-over.gif");
		preloadFlag = true;
	}
}

function calculate()
{
	var comps = document.getElementById("txcomputers").value;
	var servers = document.getElementById("txservers").value;
    
	if (comps == null)
	    comps = 0;
		
    if (servers == null)
	    comps = 0;
		
	var pc_price = 99;
	var ser_price = 135;
	
	var total_pc = comps * pc_price;
	var total_serv = servers * ser_price;
	
	var total = total_pc + total_serv;
	
	  alert('Your Monthly Total IT Support will be  :R'+total);
}

function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }