Hi,
tinyMCE, the visual editor for WordPress, has its own plugin called ‘table’ which does right this. (Searching for wordpress’ plugin can’t help you).
Just download tinyMCE from its webpage. In the archive, in folder tiny_mce/jscripts/tiny_mce/plugins is ‘table’ folder, which is to copy to your wordpress/wp-includes/js/tinymce/plugins.
Then enable this plugin by editing tiny_mce_config.php – add ‘table’ to $plugins and add ‘tablecontrols’ to $mce_buttons.
And it should be working fine.
Regards,
Locus