Changing File Structure Advice

At the moment I’ve got a WP blog sitting behind the primary pages of my sites so the files for my posts look a bit like this…

http://www.domain.com/blog/post-name

Plus I’ve got around 5-6 primary pages like…

http://www.domain.com/index
http://www.domain.com/about-me
http://www.domain.com/contact-me

…etc, etc.

I want to remove the primary pages and have WP at the root of my site which will change the format of all my 100+ posts from…

http://www.domain.com/blog/post-name

to…

http://www.domain.com/post-name

The problem I have is that those 100+ posts are all indexed by Google and attracting traffic. If I remove the /blog/ folder then essentially I am creating entirely new URL’s and my old ones will cease to exist.

Is there any method or plug-in that anyone could recommend to minimise the impact of what I’m going to do?

Many thanks