Office 2007 & Messenger Live Plus!
I installed the download of Office 2007 RTM from MSDN yesterday (after uninstalling Beta 2 of course). I can only talk about Word and Excel, since those are the two programs I use almost exclusively. I find that I am more productive in the Office 2007 environment and the menu system is more intuitive and ....... it looks great!
If you use MSN Messenger, I would suggest that you install Messenger Plus! Live. It's free and the feature allowing multiple (tabbed) conversations in one window alone is worth it.