XML / XSL

int swapPos1 = 8;//hard coded, but they do exist in the schema
int swapPos2 = 9;

System.Xml.XPath.XPathDocument xml = new System.Xml.XPath.XPathDocument("myxml.xml");

        System.Xml.XPath.XPathNavigator xmlNav = xml.CreateNavigator();

        System.Xml.XPath.XPathExpression expr = xmlNav.Compile("/Tabs/Tab");

        expr.AddSort("@position", System.Xml.XPath.XmlSortOrder.Ascending, System.Xml.XPath.XmlCaseOrder.None, "", System.Xml.XPath.XmlDataType.Text);

        System.Xml.XPath.XPathNodeIterator iterator = xmlNav.Select(expr);

        while (iterator.MoveNext())
        {
            int pos = int.Parse( iterator.Current.GetAttribute("position", "").ToString() );
            if (pos == swapPos1)
            {
                iterator.Current.MoveToAttribute("position" , "");
                iterator.Current.SetTypedValue( swapPos2.ToString() );
                continue;
            }

            if (pos == swapPos2)
            {
                iterator.Current.MoveToAttribute("position", "");
                iterator.Current.SetTypedValue ( swapPos1.ToString());
                continue;
            }
        }