A while back, I complained about the difficulty in obtaining the necessary hotfixes for Exchange 2010’s Service Pack 1.  I just took a peek at the “Hotfixes and Security Updates included in Windows 7 and Windows 2008 R2 Service Pack 1 (http://go.microsoft.com/fwlink/?LinkId=194725)” article and verified all necessary hotfixes are within. 

So if you’re planning on Installing Exchange 2010 SP1, it may save you time to install Windows 2008 R2 Service Pack 1 first.