<style type="text/css">
    .row-highlight
    {
        background-color: Yellow;
    }
    .row-select
    {
        background-color: red;
    }
</style>

<asp:GridView ID="GridView1" runat="server">

</asp:GridView>
<script type="text/javascript">
    $(function () {
        var tr = $('#<%= GridView1.ClientID %>').find('tr');

        tr.hover(
             function () {  // mouseover
                 $(this).addClass('row-highlight');
             },
             function () {  // mouseout
                 $(this).removeClass('row-highlight');
             }
        );
        tr.click(function() {
            $(this).addClass('row-select');
        });
    });

</script>

<asp:GridView ID="GridTest" runat="server" DataSourceID=... >
   <Columns>
   ...
   </Columns>
   <SelectedRowStyle BackColor="#E2DED6"/>
</asp:GridView>

<asp:GridView id="GridView1" runat="Server">

    <Columns></Columns>

    <SelectedRowStyle CssClass="selectedRowStyle" BackColor="LightCyan"
        ForeColor="DarkBlue"
        Font-Bold="true" />

</asp:GridView>