I use Outlook 2007 without any add-in. My projects have their own folders where I put any related email after dragging it to the To-Do Bar. The To-Do Bar is set up to view by category, which are my contexts. This makes using the To-Do Bar the best thing in Outlook for me: it assigns the category and a due date. Right now, I don't have due dates set, I do that in my Weekly Review. I can glance down the To Do Bar, open the context I'm in, and knock out the tasks. Plus, I can change the task to something more action oriented ("add to next version" instead of "application request 23492")
When that project is complete, I move it to an archive pst file.