Hi, I am Janko from Serbia and I am Microsoft Certified System Administrator. This downgrade can be easily performed from PowerShell using a specific command, the only thing you need to have prepared in advance is your product-ID (it is usually on the box the install CD came with or on a sticker on the server case). The server should reboot twice before the operation is completed, so it would be the best to have someone close to the server in case something goes wrong during the boot period.