I  moved my sites from one computer to another and lost all my site definitions. It seems like everytime that I move my local root folder to another location I have to redefine sites. When I moved the template folder all the pages looked awful, why is this?

The best way to avoid these sorts of problems is to do this within the site window. Dreamweaver you will notice will keep track of changes and ask you if you'd like to update links. If you move the entire local root folder, just edit your site definition (site > define sites) and browse to the new location of the local root folder on your hard drive.

Also make sure that the templates folder is at the root of your local root folder to make sure it is functioning properly!