(URL Translating) Apache, PHP, and the love of it all.... well, maybe not.

I'm going to start with a nice simple, hopefully, questions. Some of you may have seen PCWorld.com - and its urls that are like http://www.pcworld.com/news/view/0,aid,3911,00.asp. This is achieved with a product called XCache (for IIS, visit www.xcache.com), wich translates this url into http://www.pcworld.com/news/view.asp?aid=3911. Now, you can probably do this in regex, and use the mod_rewrite, but this is not available to me, so we can all forget that one right away ;-). I have created a 404-processor that does the conversion (and even checks if the resultant page exsists, by using a simple file_exists();). Apache (or was it PHP? Or a combination of the above?) used to, when you said Header ("Location: /localpath"), just serve up the content, without doing a redirect. Under Apache/1.3.17 & PHP/4.0.4 this does not happen. Is there a way to do this redirect internally - ie. the browser is not even aware that the URL is different from the one it requested, let alone the visitor. And no, frames are not really an option: because it would defeat one of the reasons I want to do this internally, which is to prevent the need to do two requests. Hopefully someone will understand this (I'm sure there will be many), and be able to guide towards something that will work. Thanks, Patrick.