Download Joomla Templates

I prefer to make my sites in XHTML but its a pain to update frequently, moreover some of my clients want to do the updating themselves. I need a CMS that is stupid easy to use, lightweight, and most importantly need one that wont be a pain in the aspect of converting my html templates into cms ones, in other words, take some snippets and stick it in existing template. I heard of something suitable some time ago but I cant find it now.
Oh and the next guy suggesting Drupal Joomla, or phpnuke is getting murdered.

At the risk of my immanent demise at your hands, there’s no "template" you can drop existing code into to make it user-modifiable. You’re going to have to bite the bullet, learn programming, and write your stuff in something that’s designed to do what you want. I won’t mention product names, but look at http://php.opensourcecms.com/ - it has most if the biggies, including "J" and "D". That’s the level at which you’re going to have to operate to do what you want - actual programming.