I am trying to create a scheduled task to convert all my .vsd files to pdf so all of our devices can read them (linux, mac, smartphones, etc..) and I would prefer not paying for something that can be done with Visio + PDFcreator.

The approach of using openoffice doesn't work with .vsd files since it's not a supported format ( Method/tools for batch-converting Microsoft Word files into PDF?)

What I've currently is this: 'C:\Program Files\Microsoft Office\Visio11\VISIO.EXE' /pt "Z:\Archive\Files.vsd",-PPDFCREATORPRINTER /nologo

That is able to open automatically the document I want and to prepare it to be printed, the only missing part is that it requires me to confirm on the printing dialog.

There's some information here: http://support.microsoft.com/kb/314392 but it doesn't explain abotu non interactive printing.