Registration help

So I have the registration form working for my website im building. But what im really wondering is how can I (on success of registration) make a folder with the name of the username and have it put a index.php file in there that I specify? Any ideas?

Something along the lines of

http://www.depthcore.com/user/1/

That but without the /1/ and instead it being the users name and having it call the default member index page