Moving site from subdomain to parent domain

Hi all,
What is an elegant and efficient way to move a new site from a subdomain to its parent domain where the existing site is located, with minimum disruption to site visitors? (The new site might be a static XHTML-CSS site, but it might be either a CMS- or Wiki-based. I am still considering the options.)
Any advice or suggestion will be much appreciated.
- marsbar

Two choices: Create a Mirror Domain of the subdomain in the Panel: Domains -> Manage Domains. And create a Mirror Domain of example.com that points to sub.example.com

Or the more thorough approach:
1) If you don't already have the fully hosted main domain set up, do so. You'll get an example.com folder in your home directory.
2) Rename example.com to old.example.com and then rename sub.example.com to example.com
3) Go through your config files and update any directory paths and domain references for the new setup.

-Scott

Many thanks for taking the time to reply and for your help, Scott! I will go with the thorough approach.
Cheers,
marsbar