Auto convert parts of links that user's post (for affiliate programs)

[007]

I want to be able to "replace" the beginning of some URL's in posts with an affiliate URL. By replace, I mean replace the actual link only through the replacements system. I want the links in the threads to remain the same, but to be replaced on page load.

For example:

Take the following site

http://site.com/?article=4324

And redirect links posted with the following:

http://affiliatesite.com/?affiliate...m/?article=4324

But using javascript to show the non-affiliate link in the status bar.

Basically I need to replace

http://site.com/?article=

with

http://affiliatesite.com/?affiliate...e/com/?article=

Leaving the last number off, so when different articles are linked to they will all work with the replacement? Does that make sense? Any suggestions?

I think it can be hardcoded somewhere, but what file would I put it in? If someone wants to make a real hack out of it, that would be awesome too.

Thanks.

~006