Hi Sam,
One of our very large clients has just installed a Windows Server 2012 R2 as a private cloud install with an RDP connection for all (some) 100 concurrent Adagio users, and is being used primarily for Adagio. Our Adagio site is working great (beyond incredibly fast) but required planning to ensure that this was a good solution. Probably more than you will get from this forum. (no offense to the valued responders and readers).
Our site has been configured with sufficient RAM, and sufficient Cores to meet and exceed the requirements of Adagio and other defined applications, based upon our analysis and our contracted experts.
We didn't respond because we didn't know what Windows 2012 Essentials was? Windows Essentials is often identified as the Microsoft low end Antivirus solution that should not be used with Adagio on any networks.
Replacing an existing server with Windows 2012 Essentials, on an IBM box? Sorry but we are not that close to the buzz words of the hardware and networks to offer constructive comments or advice, without more details and costs. There are a lot of issues that need to be addressed if you are looking at replacing a server, and best discussed concurrently with hardware and Adagio experts.
We hope you have no problems installing and operating Adagio on the new server.
Best,
Brian