Thank you for your answer, we already have the root folder organized in subdirectories but i can't find the drectory view you are talking about.
In the "View" combo of the AP i only have two options "Thumbnails" and "Details"; if i select "Details" and then in the field "Sort by" i select "Document path" i get something similar to what i want, that is a browsable tree of all my direcotries and reports (i hope it can be filtered with DMS security, still have to give it a try).
Is this the "directory view" you are talking about?
Anyway the combination of View="Details" + Sort By="Document path" could be a solution for me, the Category way instead is not enough because i am not sure you can set sub categories in that way.
My server version is 10.00.8815.6.