The existing system has many reports . Using a free pdf printer like dopdf or cutepdf the user can open the report , choose the pdf printer , type in the filename and save t
Install Adobe Acrobat Professional and choose "Adobe PDF" as the printer.
Following up on Stijn Sanders's reply: The latest version of ReportBuilder from Digital Metaphors now includes native PDF export, as well as "silent" saving of the PDF, and e-mailing of the report. You are correct, however, in that you would have to convert all of your reports to ReportBuilder. It may be worth looking into, though, depending on the complexity and number of reports in your project. We converted ours from Rave Reports and never looked back.
The free, open source PDFCreator can function as a virtual printer but it's also usable via COM. The default setup even includes COM examples.
You can check the COM samples in the SourceForge SVN repository right here: http://pdfcreator.svn.sourceforge.net/viewvc/pdfcreator/trunk/COM/
Delphi and ActiveX get along superbly so you should not have much trouble.