Download Microsoft Virtual Server R2 Enterprise Edition
Yes, now you can, for free!
From Microsoft’s webpage:
Microsoft Virtual Server 2005 R2 is an ideal, production-quality tool for consolidating multiple workloads onto a physical server, allowing organizations to make more efficient use of their hardware resources. Built upon Microsoft Virtual Server 2005 SP1 and bolstered with new functionality, Virtual Server 2005 R2 enables IT organizations to enhance their administrative productivity and rapidly deploy new servers to address changing business needs through automated deployment and configuration of connected virtual machines that are easily administered with standard server management tools. Virtual Server 2005 R2 is an extensively tested and well supported virtualization solution that is supported both by the broader ISV community and by Microsoft in conjunction with its server operating systems and applications. Because it is part of the Microsoft Windows Server System, Virtual Server 2005 R2 is designed to integrate seamlessly with your other server infrastructure investments.
Supported Operating Systems: Windows Server 2003 R2 Datacenter Edition (32-Bit x86); Windows Server 2003 R2 Datacenter x64 Edition; Windows Server 2003 R2 Enterprise Edition (32-Bit x86); Windows Server 2003 R2 Enterprise x64 Edition; Windows Server 2003 R2 Standard Edition (32-bit x86); Windows Server 2003 R2 Standard x64 Edition ; Windows Small Business Server 2003 ; Windows XP Service Pack 2
Supported Host Operating Systems: Microsoft Windows Server 2003 Standard Edition, Enterprise Edition, or Datacenter Edition or later; Windows Server 2003 Standard x64 Edition, Enterprise x64 Edition, Datacenter x64 Edition or later versions; Windows Small Business Server 2003 Standard Edition or Premium Edition; Windows XP Professional Service Pack 2 or later (for non-production use only).
Intel Celeron, Pentium III, Pentium 4, Xeon; AMD Opteron, Athlon, Athlon 64, Athlon X2, Semprom, or Duron processor
Minimum CPU speed – 550 MHz
Minimum of 256 MB of RAM (512 MB or more is recommended. Additional memory will be required for each guest operating system)