<p>I have built a MS Access 2007 application that can create reports files in various formats (PDF, XLS, CSV, XML).<br>
I would like to allow the creation of these reports to be accessible from a web page where users would just click on a link and get a download of the report produced by my Access application.</p>

<p>I would like to keep it simple and I'm not interested at this stage in rewriting the data processing in .Net. I'd just like to find a way to automate the creation of the user report to return a file that can be downloaded.<br>
In essence, my Access application would act as a web service of some kind.</p>

<p>The web server is IIS on Windows 2003.</p>

<p>Any pointers or ideas would be welcome. I'm not well versed in IIS administration or ASP pages.</p>

This is kind of a round about way to achieve what you're asking.  You can utilize the free version of sql server express 2005 or 2008 advance edition which includes the reporting services component.  Using the report generation tools you can convert your access 2007 reports to sql server reports and have those reports feed off of the access database.  You can also go to the extent of migrating the database to sql server as well if you wanted to go that route.  Reporting services will generate pdf, xls, csv and xml formats as output for your reports and you can generate those reports just by passing the parameters in the url to the server which will return your report in the format requested.
Link to sql server 2008 express advanced edition:
http://www.microsoft.com/express/sql/download/