In my opinion any file can be converted to a PDF. Just install PDF creator or similar and when you choose your printer, make sure you choose PDF Creator.
Hope that helps!
c/ Diego de Leon, 47
As Roberto mentioned, you can convert just about any type of file to a PDF. What application are you authoring your document in? You may also want to reach out to the printing company you're going to use to see if they have any preferred settings as it pertains to the PDF you're planning to create.