One topic that I don't feel is covered in the GTD and Outlook whitepaper is how to separate personal and work items in Outlook. Initially when I configured outlook I set up a category @Personal that I would use for personal items. So I was assigning multiple categories to some items. For example, an action to post new pictures on my personal website was a task marked as @Computer and @Personal. But as the number of actions grew and I had the tasks grouped by category the list became unmanageable because items were listed multiple times. It was very annoying during the weekly review.
So, I have eliminated the @Personal category and for all personal actions I just check the "Private" checkbox on the Outlook task. Then in the Task view I have added the "Sensitivity" column which shows "Normal" for my work items or "Private" for my personal items. This allows me, during the work day, to do quick scans of my task list skipping the personal items.
I know some people have said that they keep two independent systems but that seemed like too big of a headache for me and the way I currently have it implemented in Outlook really seems to be working for me.