This application allows you to run multiple virtual machines or virtual servers on a single physical server.  "Why would I want one or more fake servers on top of a real server?"  If you aren't familiar with this topic, it's too broad to get into all of the details here, but we'll hit a few highlights.

Here are some of the benefits of Virtual Server:

• This allows you to consolidate multiple servers into a single physical server while still keeping the servers isolated from each other.  In short, you can save money on hardware.
• It allows you to keep legacy systems functioning even when they don't support modern operating systems or hardware anymore.  For example, The Community Foundation of Sarasota County (CFSC) has an old CRM/accounting program called TracStar that only runs on the Windows 9x platform.  They periodically want to access it for archival purposes, so I setup a Windows 98 virtual machine with TracStar.
• Virtual Server makes disaster recovery a lot easier!  Virtual Servers have identical virtual hardware.  Therefore, you can copy a Virtual Server to an external hard drive and move it to another physical server without having any driver issues.  Therefore, when a physical server goes down, you can get the virtual server up and running easily on another physical server.  This is one of the big reasons that CFSC is virtualizing its servers.
• Virtual server allows for easy testing.  Let's say you have to install a major application update.  You can make a copy of the virtual hard drive file before you perform the upgrade.  Then if the upgrade fails, you can simply roll back to the original virtual hard drive file, and it's as if nothing ever happened.  You don't have to mess with complicated backup software in order to perform the recovery.  Believe me, I've already used this feature on more than one occassion.
• Virtual Server makes it easier to perform full backups.  You can shut down the virtual server, and then make a copy of the virtual hard drive file.  You don't have to worry about purchasing an expensive open file agent for your backup software either, because all files are closed when the virtual server is offline.

Virtual Server technology used to be pretty expensive when the only game in town was Citrix.  However, Microsoft released their Virtual Server 2005 R2, Enterprise Edition product for free this year!  Now small businesses can take advantage of technology that used to be available only to enterprises with deep pockets.

Virtual Server is definitely a technology worth investigating.  If you want to learn more, go to the following link: http://www.microsoft.com/windowsserversystem/virtualserver/default.mspx