Then I strongly advice to use FusionDeskPro.
You can organize projects with a tabbed user interface, every main project a tab, and inside the project you can create folders and subfolders and ad tasks to these. Every task can be set up with Priority, Status, Start/End time, estimate costs (based on elapsed time and hourly costs), people to be assigned to.....
You can even create an invoice for your customers.
Thanks, I'll check it out!
HH