Well.. I would think that by default when you deselect a top-level category, then it's sub-categories will de-select. However there is nothing preventing a user from then selecting a sub-category only. Or the other way around. If you don't care about games you would select OS2008 / Maemo 4 / Chinook - Diablo, and then De-select "games" underneath.

At least.. that was my thought. It didn't seem confusing to me. If we need to add another category to it then ok.. but we don't want to go too overboard - the idea is for the structure to be as simple as possible.. KISS-style. So whatever way to make it more along those lines I'm up for. It would be nice if we had a little more input from some more people.