"strange" relations between articles and multiple categories

Hi, i would appreciate any help about a task i have to complete.

I have this scenario:

A list of projects (articles) belonging to two different kind of categories : services and sectors.
Each article has meta data.

When i show a project, i need to show, on the right column, a list of the related projects, but shown in two steps:

First step, i have to show oen block for services and one block for sectors - not articles, just categories - that contains articles (projetcs) related with the article shown

Second step, clicking on one of the sectors or service containing relateds projects, i have to "change" the clicked block (sectors or services) with a block listing the related projects.

The behaviour i need is the same you can find on www.burohappold.com . If you click on a project, you will find the right column changing and showing services/sectors/projects according to the item you've clicked.

... i offer a dinner in Rome for the person who will give me the solution !

Thank You
Maurizio