I created a tutorial about Error Handling in RapidWeaver Websites which explains how to make a custom 404 page with useful links to help your visitors when a 404 does occur, and how to use 301 redirects in your .htaccess file to assist with page renaming or re-pathing.
A 301 redirect just points the visitor at the new file you specify, when they try to visit the old file. Useful for adds, moves and changes. The tutorial has a lot more detail than what is in this post, so please take a look at it. I hope it is useful to someone.