I am running it on both of my servers (Application and Database). I am running Micros 9700 version 4.0.065 Service Pack 1.
OS: Windows Server 2008 R2 SP1 (64 bit)
I would suggest backing the system up (if possible), then only updating that Security update then running for a week or two, then update any other. Because of PCI compliance you will need to keep your system up to date (with Security, High/Med updates at the very least).