Althea wants to know what the difference is between Virtual PC and Virtual Server, and when she would use one versus the other. The fundamental difference between Virtual PC and Virtual Server is that Virtual PC is designed for desktop (or "client" or "PC") operating systems and Virtual Server is designed for server operating systems. As a result, the usage scenarios for the two products are correspondingly different. There are a few feature differences as well. This article covers the major functional differences between the two products.

Supported operating systems

For Virtual PC, both the host operating system (the one you install Virtual PC itself on) and the guest operating systems (the ones running inside virtual machines) will be desktop operating systems. Supported host operating systems include Windows XP Professional, Windows 2000 Professional, or Windows XP Tablet PC Edition. Supported guest operating systems include these plus a number of others, such as Windows 98 and MS-DOS 6.22. See the Virtual PC documentation for a complete list.

For Virtual Server, the host operating system and the guest operating systems will be server operating systems. Supported host operating systems are Windows Server 2003 (Standard, Enterprise, and Datacenter Editions) and Windows Small Business Server (Standard and Premium Editions). Supported guest operating systems include these plus Windows 2000 Server, all editions except Enterprise as well as Windows NT Server 4.0 Enterprise Edition SP6a. See the Virtual Server documentation for more information.

Usage scenarios for Virtual PC

Some primary usage scenarios for Virtual PC are:

  • Support for legacy desktop applications. For example if you have applications  that were designed to run on Windows 98, but won’t run on your new Windows XP machine, you can run Windows 98 and your application in a virtual machine. Ben Armstrong uses Virtual PC to run his favorite DOS-based computer games. (For more info, see Ben's blog at http://blogs.msdn.com/Virtual_PC_Guy.)
  • Help desk. If you're a  help desk technician, you could set up a variety of desktop environments inside virtual machines to duplicate those of you client’s, so you could reproduce problems when clients call in.
  • Desktop application testing. If you're a developer, you can use virtual machines to test desktop applications in a variety of operating system environnments.
  • Training. If you're a trainer, you can set up your training programs to run inside virtual machines. This way you can offer more types of classes. In addition, you can set up the virtual machines to discard changes that were made during the class. This reduces setup time dramatically.

These scenarios are described in detail in the white paper at: http://www.microsoft.com/windows/virtualpc/evaluation/techoverview.mspx.

The uses that you can find for Virtual PC are limited only by your resourcefulness, though. For example, my co-worker Nehar has Virtual PC set up for his wife and kids to use for browsing the Internet. That way he doesn’t have to worry about anything they download because it won’t affect the host operating system. If the virtual machine get’s corrupted or infected, he can simply delete it and start over.

Usage scenarios for Virtual Server

Some primary usage scenarios for Virtual Server are:

  • Test and development for server applications. You can use Virtual Server in situations that require rapid and frequent server reconfiguration, as required with development and testing, product demonstrations, and training.
  • Application migration. You can move server applications running on older hardware and operating systems, such as Microsoft Windows NT® Server 4.0, onto virtual machines on newer, more resilient systems running Microsoft Windows Server 2003 operating systems, without rewriting the applications.
  • Server consolidation. Many companies have departmental and branch office servers that are underutilized. You can consolidate applications that require different server operating systems onto a single physical server to reduce the number of physical servers you need to maintain.

Other differences between Virtual PC and Virtual Server

Virtual Server provides a few features that aren’t available in Virtual PC:

  • Remote Management. You can administer Virtual Server remotely by using the Administration Web site.
  • Scalability.  Virtual Server scales across multiple processors (although in the current release each virtual machine can take advantage of only one CPU).
  • COM API.  You can manage Virtual Server and its virtual machines by using the COM API. For more information, see the Virtual Server SDK that ships with the product.
  • SCSI support. Virtual Server provides SCSI support.
  • Multiple CD-ROM drives: Although Virtual Server allows for virtual machines with multiple CD-ROM drives, Virtual PC supports virtual machines with only one CD-ROM drive.

On the Virtual PC side, Virtual Server does not include an emulated sound card in its virtual machines, while Virtual PC does.

That about sums it up as far as important functional differences. I hope this answered your question, Althea.