One of the things I enjoy about a subscription to MSDN is access to all of the latest versions software. So when Installing Office 2007 some time ago, I installed OneNote as well. I did not get the point of this application at first, however I have found OneNote to be a useful tool for keeping track of my To Do items, as well creating a detailed list of Items for a specific project I am working on.
What I find especially useful is the ability to create cascading to do items. Outlook provides a task list, but there is no way to create sub items.
In addition to an overall to do list, I use it to as my notebook for any applications I am working on, server information and passwords, and any general information I want to keep track of.