I use an iMac and Office 2008 at work. Just upgraded to Snow Leopard. Most of our files are saved on a Windows server. Previously, working on files stored on our server in Office 2008 was unbearable. Constant beach balls and lockups. Now, Office (particularly Word and PowerPoint) work reasonably well with these files. The files open quickly, and I can scroll through longer documents without much hesitation. I realize that I am judging the improvement based on a very short period of time, but the problems with Office in Leopard would manifest themselves very quickly. Upgrade to SL worth the money (well, my employers!) for me so far on this basis alone.