Google's Matt Cutts has an interesting video up (one of many) on the Google Webmaster Central YouTube channel that deals with switching to a new content management system and how that can affect search engine rankings. Someone asks:

We are changing a farily large HTML site to CMS. What are the essentials to keep in mind so that we do not lose our search rankings?

Essentially the answer to the question is that you should test the waters before going all out with the entire site. When you're changing a lot of elements on your site, it can affect rankings, but more than likely, you will be fine.

The biggest piece of advice that Cutts offers is, "Try not to launch all of this at once."

"For example, if your CMS means that your layout has to change, you can mock that up," he continues. "You can try to make it so you change your HTML so that it looks like it would look like from your content management system. And then make sure that your rankings don't change. They shouldn't change very much at all, but you know, if you change a whole bunch of stuff on your page, that can affect how Google scores it."

Cutts suggests changing one directory at first to sort of "dip your foot into the water." It's a good idea to do a mock-up first and then:

- Do some A/B Testing
- Gauge users' reactions
- See how it affects search engine rankings

You can try changing one directory at first almost like "dipping your foot in the water." Basically, you don't want to spend a whole lot of time redesigning your site and changing it over to a new CMS, only to find that it kills your rankings. Test the waters, then if looks good, go for it.