I recently had to update a couple of my clients computers to the latest service pack for Exchange 2010. SP3 recently was released which was a major update to Exchange. This updates resolves several issues so it should not be skipped. However before you run this update, make sure you have a valid backup of your current Exchange server. I was fortunate enough to not have to use the backup, however I did run into a bit of a scare on my first run of the update. The average time for this update is estimated about 30 minutes. The first server I ran this update on it ran for over 6 hours! Yes I said over 6 hours! I started this update just after 8pm, and it was still running at 12am. I decided I was going to let it run and wake up at 5 am. The update finished in 6 hours 12 minutes. I rebooted the server and the server and Exchange are working properly, but you can easily understand the scare. I then had to run the update on another clients server, and it ran for only 27 minutes! It was quick and fast and after the reboot, again everything ran smoothly. The moral of the story is be prepared for it to either take awhile, or be quick and easy, and if all else fails, make sure you have that backup!!!