If you use Office 2007 (well done! Doesn't the Ribbon make life easier once you get used to using it rather than digging through menus) then you'll be happy to know that Service Pack 1 is now available to make it all even better.
The thing I noticed out of the box is that Outlook is more responsive than the initial version but I suspect I'll find more goodness the more I use it. Of course, you can always check out the Knowledge Base article for more info
You can download it here or grab some of the related service packs: Office Language Pack 2007 SP1; Office Project 2007 SP1; Office SharePoint Designer 2007 SP1 and Office Visio 2007 SP1