My actual data.d contents:

{"d":[{"ID":1,"Name":"Justin"},{"ID":2,"Name":"Bob"}]}

my actual JavaScript:

        var ViewModel = function () {
            var self = this;
            self.items = ko.mapping.fromJS([]);
            self.refresh = function () {
                $.ajax({
                    type: "POST",
                    url: "Default.aspx/GetProducts",
                    data: "{}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (data) {
                        ko.mapping.fromJS(data.d, self.items);
                    }
                });
            };
        }
        var viewModel = new ViewModel();
        $(function () {
            ko.applyBindings(viewModel);
            viewModel.refresh();
        });

my actual HTML

    <table data-bind="visible:items.length > 0">
        <thead>
            <tr>
                <th>ID</th>
                <th>Name</th>
            </tr>
        </thead>
        <tbody data-bind="foreach: items">
            <tr>
                <td data-bind="text:ID"></td>
                <td data-bind="text:Name"></td>
            </tr>
        </tbody>
    </table>