I'm not going to bother with a lead-in this time: Office 2003, running on Windows XP (I'm assuming that it's this bad on Vista as well), is the worst dogs-breakfast example I know of, of the fact that if you don't give people consistent and clear guidelines, you end up with a midden-heap of conflicting ideas.
Let's have a breakdown look at how each individual component - Word, Access, Excel, Outlook (I can't be bothered opening up PowerPoint to compare) - handles multiple documents:
Word: Each document has its own window, and own icon on the task-bar.
Outlook: Each application (mail, calendar, tasks, address book) has to be jiggled around in the same window, although you can open them in a separate window, when they each get their own task-bar icon.
Access: Each database looks as though it exists in its own window, but actually each open form/query/table whatever gets its own task-bar icon and, when you have multiple databases open (pity me, people), they aren't in any order so if you're in a hurry you are faced with trying to work out which one you want. This alone is stupid.
Excel: Each open spreadsheet uses the same window. You get one task-bar icon, you get one entry in the alt-tab switcher, you get a confusing mess. No quick switching from one to another if you want to compare, or carry over TOIL between timesheets, or whatever. Unexpected, and infuriating. Just to add insult to injury, Excel appears to be the only application that doesn't respect printer default settings. I shit yet not.
Who's responsible for this? And how can we enact revenge?