The nofollow attributes are good if you are trying to implement the silo structure, are you planning on implementing more levels to the site or is it staying in the 7-10 page bracket?
If you're planning to expand the website I would take that into consideration when implementing your structure for SEO, keeping in mind that you need to make space for 2nd, 3rd, 4th levels etc in a tree structure if you are going to have a big website.