I have 10 citrix PS4.5 servers all running Server 2003 R2 SP2. PS4.5 has never been updated with any of the roll up updates or hot fixes and i have read many bad stories about it. As i am beginning my process in to this upgrade i have a few questions. 1. Is it possible to upgrade one server at a time or do i have to do all servers at the same time? 2. Do i have to upgrade the data store/collector before any of the other servers? 3. Is it truly just as simple and download, install , reboot and your done or is there a lot more to it?