I would recommend to anyone who has people linking in from other websites; to prevent broken links, that you use a redirector.
Such as in your root create a simple php file like "go.php".
In this php page, use a simple set of "if" statements or a loop and array.
When people link to you have them use this to get to the target page.
Then someone links to:
http://www.yoursite.com/go.php?loc=forum
They get the forum as long as you change the location of it in the "go.php" page.
I am not going to give you any code examples, you people are not idiots, and stealing code is cheating in my book. Learn it, write it your way, and make it work.
Later all,
-JL