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
Anna, as an aside in the comments you mention you're using an older version of ReportBuilder - have you looked at the Waler TExtraDevices component? I don't have it to hand but I seem to recall back in the day we used this to get output from ReportBuilder to PDF, and because of the way it makes ReportBuilder think it's a text device, you can do this without any previewing or interaction on the part of the end user.
Having said that, you're looking for a general-purpose method that would work with QuickReport and Excel. I really think you're going to end up with some kind of 'PDF Printer' and forcing your reports to this 'named printer'. You might be able to set-up PDF Factory such that it takes the output filename from the document title, etc - but I do think you're always going to have a bit of user interaction no matter how hard you try. :-(
Do let us know what you do, as this is a problem I've had myself and never managed a very satisfactory solution. I'd be interested to see what you choose to do!