Moving a sub-site from MU to SU

So, I have a site at http://zdecade/davidgewirtz which is a sub-site on a WP multi-site installation. The Zdecade site is the main site.

I want to create a single-site WP install (no multisite at all) that is just davidgewirtz.com.

Now, a few gotchas. DavidGewirtz.com should have gone to the zdecade/davidgewirtz site, but it's intermittent. Something's not quite right in cPanel.

So, while some pages and, more importantly, graphics, link to davidgewirtz.com, others are at zdecade.com/davidgewirtz.

So, what's the most painless way for making the move, properly moving the domain to davidgewirtz.com, not screwing stuff up, keeping my theme configuration, and all the rest?

I'm using a WPMU theme, but off the top of my head, can't remember which.

Oh, and hi everyone. Been busy the last few months. Hope things are good!