function toggleSiteMap()
{
        var siteMap = document.getElementById('siteMap');
        var pageFooter = document.getElementById('pageFooter');
        var pageFooterTop = 0;

        if(siteMap.style.display != 'block')
        {
                var bodyWidth = Number(document.body.offsetWidth);
                var bodyHeight = Number(document.body.offsetHeight);

                if (pageFooter.offsetParent) {
                    pageFooterTop = pageFooter.offsetTop
                    while (pageFooter = pageFooter.offsetParent) {
                           pageFooterTop += pageFooter.offsetTop
                    }
                }

                siteMap.style.display = 'block';
                var siteMapHeight = Number(siteMap.offsetHeight);
                var siteMapWidth = Number(siteMap.offsetWidth);
                siteMap.style.display = 'none';
                var pageFooterHeight = Number(document.getElementById('pageFooter').offsetHeight);

                var topPosition = pageFooterTop - siteMapHeight;

                var leftPosition = (bodyWidth - siteMapWidth)/2;

                siteMap.style.position = 'absolute';
                siteMap.style.top = String(topPosition) + 'px';
                siteMap.style.left = String(leftPosition) + 'px';

                siteMap.style.display = 'block';

        }
        else
        {
                if(/MSIE/.test(navigator.userAgent))
                {
                        siteMap.style.display = 'none';
                }
                else
                {
                        Effect.Fade(siteMap, {duration:0.5});
                }
        }
}