Be careful using redirect techniques like this. Search engines are increasingly associating redirects with hijack attempts. Meta-refresh tags and redirects within .htaccess files both seem to have this sort of problem.
If you're interested in maximizing the search engine ranking of your sites, you're better off creating a simple splash page with a link to the CMS portion of your site. It's an additional click, but is fairly important for SEO and ranking.
I switched to this simplified method with my Joomla site here: http://teamshocker.com/ and it increased my rankings.
You can find more details here: http://www.loriswebs.com/hijacking_web_pages.html