I have banged my head against my desk long enough. What I want to do seems easy enough, but with research, seems impossible. The reason might be that I am not a php expert.
The ultimate goal is to have a checkbox list of categories in Wordpress. The user will check 2 or 3 categories and that will bring them to an archive page that will display the articles tagged under the categories they chose. Is this possible in php/wordpress? Right now wordpress default is to only display one category at a time.

I have found solutions to show multiple categories on a page through query_posts. This solution is limited because I would have to say which categories are displayed in the code of the page. Also this way it shows all articles in both categories. I need it to show articles that are tagged with both categories, not either or.

Any suggestions? pointing in the right direction?