Activating an OLD theme to a new StudioPress Theme. SEO Considerations

[loudcow]

Hey there!

My client desperately needs a site rehaul. The look, navigation and functionality are terrible. From a CMS perspective, it takes a coder to change ANYTHING.

It's built on wordpress but the theme is, as explained above, shocking.

I want to change it to a new Studio Press theme. However, they are ranking very well in their market and I'm super-scared I will dismantle the good SEO work they have already done.

Additionally, I want to ensure the site's downtime is kept to an absolute minimum

Can anyone give me some advice on the best way to go about doing a transfer?

me