It depends - usually if you're sending a file to a printer for business cards, they're going to want a PDF file - more specifically, a PDF/X flavor. And they'll want a high-definition file - high-res if you're using bit-mapped graphics, so you'd best use either a vector graphics file (created in Adobe Illustrator or the like) or something like Photoshop that will allow you to create a 300-dpi image.
I don't know that the built-in Mac PDF maker will allow you to set the quaility. I would talk to your printer first and see what they suggest: many printers are online and have specific guidelines for submitting files.
Good luck,
Clinton