Sharepoint upload image and pdf from one form

Question

I have a Sharepoint 2007 process where the user uploads an image to a Picture Library and then uploads a PDF to a Document Library. The Document Library list contains a hyperlink column where the user can specify the URL of the corresponding image in the Picture Library.

What I want to do, however, is have one form where the user can upload both the image and PDF and have Sharepoint populate the hyperlink field automatically. Is it possible to create something like that as a custom content type, so the user can select it from the New menu? Can I do something like this in SP Designer, or do I need to use Visual Studio?

Any example code would be helpful.