Numeric textbox javascript...

    <input type='text' onkeydown='text_keydown(event)' />

    <script language='javascript' type='text/javascript'>
    function text_keydown(e) 
    {
        var key; 
        document.all ? key = e.keyCode /*IE*/ : key = e.which /*FF*/; 
        if(!(key > 47 && key < 58) && key != 8 && key != 37 && key != 39 && key != 16 && key != 46)
        {
            cancelevent(e);
        } 
    }

    function cancelevent(e)
    {
        if(window.event)    // IE
        {
            window.event.returnValue = false;
        }
        else    // FF
        {
            e.preventDefault();
        }
    }
    </script>