function checkUsers(){

	if (document.frmSingUp.userName.value != ""){

		var alphaExp = /^[0-9a-zA-Z]+$/;
		if(document.frmSingUp.userName.value.match(alphaExp)){
			//return true;
		}else{
			alert("Only Letters/Numberes Allowed in User Name");
			document.frmSingUp.userName.focus();
		}

		var ajaxUserRequest;  // The variable that makes Ajax possible!
		
		try{
			// Opera 8.0+, Firefox, Safari
			ajaxUserRequest = new XMLHttpRequest();
		} catch (e){
			// Internet Explorer Browsers
			try{
				ajaxUserRequest = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
				try{
					ajaxUserRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e){
					// Something went wrong
					alert("Your browser broke!");
					return false;
				}
			}
		}
		
		var ajaxUserImageDisplay = document.getElementById('userimage');
		ajaxUserImageDisplay.innerHTML = "<img src='images/spinner.gif'>";
	
		// Create a function that will receive data sent from the server
		ajaxUserRequest.onreadystatechange = function(){
			if(ajaxUserRequest.readyState == 4){
				var ajaxDisplay = document.getElementById('myuserName');
				ajaxDisplay.innerHTML = ajaxUserRequest.responseText;
				
				ajaxUserImageDisplay.innerHTML = "&nbsp;";
			}
		}
		
		var myuserName = document.getElementById('userName').value;	
		var queryString = "?userName=" + myuserName;
		
		if(myuserName != ""){
			ajaxUserRequest.open("GET", "checkusers.php" + queryString, true);
			ajaxUserRequest.send(null);
		}else{
			alert("Please Enter User Name!");
			document.getElementById('userName').focus();
		}
		
	}else{//end if
		alert("Please Enter User Name!");
		document.frmSingUp.userName.focus();
	}
}