function initAjaxRequests()
{
    Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(_beginRequest);
    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(_endRequest);
}

function _beginRequest(sender, args) 
{
    ShowProgressBar();
}
		
function _endRequest(sender, args) 
{
    HideProgressBar();
}

window.attachEvent("onload",initAjaxRequests);