I am currently working on a project to create simple file uploader site that will update the user of the progress of an upload. 
I've been attempting this in pure python (with CGI) on the server side but to get the progress of the file I obviously need send requests to the server continually. I was looking to use AJAX to do this but I was wondering how hard it would be to, instead of changing to some other framerwork (web.py for instance), just write my own web server for receiving the XML HTTP Requests?
My main problem is that sending the request is done from HTML and Javascript so it all seems like magic trickery at the moment.
Can anyone advise me as to the best way to go about receiving these requests on the server? 
EDIT: It seems that a framework would be the way to go. Would web.py be a good route to take?
There's absolutely no need to write your own web server. Plenty of options exist, including  lightweight ones like nginx.
You should use one of those, and either your own custom WSGI code to receive the request, or (better) one of the microframeworks like Flask or Bottle.
Creating a python web server to recieve XML HTTP Requests