use wpdb outside wordpress.. or can i do this on a different way?

Hi people,

I’m trying to make my site a bit more complex by using jquery..

Now i think about adding some kind of reveal button.. if they press on it then the content of the post will show.

So i’ll using the ajax/post methods of jquery, but then you’ve guessed it.. the url. It will be a php file file which returns the content, but that content will be of a post in the wpdb.

So is it possible to use the wpdb in that php file? Or where do i need to place the file to make it work???

Thanks in advance!