You might want to be careful before you dive into themes. Check my experiences: This Jag is a dog, again!
* Be sure you have the proper version of Aquafix before you begin.
* Always be sure your theme is compatable with your OS version.
* If you ever update your OS, just dump your themes and start over.
Or...
Save yourself the potential headaches and avoid themes.
I've never had issues with themes but have had some 'questionable' results on a friends machine. Nothing major. No slowdowns on either of the machines i use either.