if(typeof(XMLHttpRequest) == 'undefined')
var XMLHttpRequest = function()
{
    var request = null;
    try
    {
        request = new ActiveXObject('Msxml2.XMLHTTP');
    }
    catch(e)
    {
        try
        {
            request = new ActiveXObject('Microsoft.XMLHTTP');
        }
        catch(ee)
        {}
    }
    return request;
}

function ajax_request(url, data, callback, context)
{
	var request = new XMLHttpRequest();
	var async = typeof(callback) == 'function';

	if(async) request.onreadystatechange = function()
	{
		if(request.readyState == 4)
		{
			var response = request.responseText;
			callback(response);
		}
	}
	request.open('GET', url, async);
	request.send(data);
	
	if(!async)
		return request.responseText;
}