Different default images in same content type

I'm working on a site now that displays a slideshow with the latest added content. The slideshow shows an image, the title of the article and the name of the category. It would be ideal to have just one content type called article where the category could be set dynamically in a drop-down menu. The problem is that I'd like different dynamic images depending on which category was chosen. Is this possible to achieve or is there some module that could help me do it?

A possible solution to this would be to have an archive of images that I already uploaded which users could chose from when creating a new post. WIth the basic module you only have the option to upload a new file or use default. Is there a module that lets the poster chose one of the already uploaded images when creating an article?

Right now I'm solving this by having different content types for each category but there must be a more flexible solution.