How do I change template in Powerpoint 2007?

Hello experts,

Let's say I have a 50 page presentation with a certain template (say Template1), but I would like to switch to another template (Template2) (I accept problems with alignment, page structure, etc)

Normally, I open this presentation (with Template1) and create a new one with Template2. Then I copy and paste the content from the first to the newly created one and modify where necessary.

Is there a better way to do this?

PS: Notice that I am not doing anything with Slide Master, I just want to change the template completely.

Thanks