How do I use Outlook 2007 collaboratively to share tasks, notes, calendars, etc. amongst multiple people?

I just got Office 2007 Ultimate, thrilled that it would allow for collaboration. But I cannot figure out the best way to create shared folders for tasks, notes, calendars, etc. I read about SharePoint, but that looks like it requires additional, expensive server software. Then I set up MS Groove which seems great, but I've found no clear way to integrate it with Outlook. Do I have to switch over to Groove's clunky interface in order to access such shared items? Or is there some way to create folders in Outlook which are set up to be shared via Groove? Or is there some other way to collaborate in Outlook 2007 which I'm just missing? Help!

What you are talking about is a feature of Outlook that requires Microsoft Exchange Server to work. Outlook is just a mail client and Exchange is the mail processing system (and central collaboration tool). That is the only way you can create shared folders (they sit on the Exchange server), tasks, notes, calendars, etc. Without a shared mail server, the users cannot communicate this interactively with each other. Of course you do not need to be on the same mail server to send meeting requests to other people, but they cannot see your calendar (unless you are on the same mail server).
The main reason for this is that each user has their own Outlook PST file.

i'm trying to do the same thing. I need my assistant to be able to access everything on Outlook. I know there is a way and the first answer is good but i need a step by step :) when you find out let me know!