I have a website right now with about 120 different pages, its got a PR of only 1 but about 90% of my traffic comes from search engines. I now just had a completely new one made for me and I have to replace it with the old one. All of the pages have new addresses and directories, so what is the best way to make this transformation without messing up google and all? Also when I make this transformation how can i work on the site and modify it while general traffic views some kind of "Under construction" page? Thanks for all your help!
MOst important thing for you to do is create 301 redirects from your pages on your old site to the relevant pages on your new site. That way you can keep most of the SEO benefits you have achieved so far
Agreed. Use 301 redirects to point your old pages to the new ones. I also hope the new pages actually took advantage of the powerful benefits that lean, mean, semantic markup can provide.