Thanks for the responses. I haven't used tabs before - I'll have to look into that.
As far as the nested forms go, though, they are synchronized subforms. The parent form is set to Single Form - this is where I select the category.
The first subform (child) is all attributes associated with the category. The second subform (child) is all products within that category with that attribute. The third subform (child) is all products in that category without that attribute. Then the second and third subforms each have subforms (grandchildren?) which just show information about the products - product name, etc. All of the children and grandchildren are set as Datasheet view. The grandchild form is only visible if you click on the plus sign next to the record in the child form.
Obviously, this is my own terminology. I'm still learning all the lingo. This is my very first database project (I've been using Excel extensively for years, but never Access - my projects got too big for Excel, so I'm jumping in to the database world.) Thanks for your patience.