Adding Filenames to Metadata

[Sally Johns]

I am currently in the process of organizing all my photo files and compiling them on Aperture. However, I already have thousands of older image files that need to be transferred. How do I go about first adding the original filenames to the metadata before I pull them into Aperture. Is there a program that can do this for me??? Or do I really have to manually go in?
Thanks,
Sally