Xen is state-of-the-art virtualization on the PC - and it is even open source. With a high performance mainly due to it's architecture with the hypervisor and it's support for hardware virtualization - Xen sets a new standard for virtualization software.
Already used in many data centers Xen has shown that it is stable and a product you can rely upon.
It matches almost any feature you get from commercial virtualization software - but includes the most advanced such as virtual machine relocation and per virtual machine resource guarantees.
The Xen hypervisor, the powerful open source industry standard for virtualization, offers a powerful, efficient, and secure feature set for virtualization of x86, x86_64, IA64, PowerPC, and other CPU architectures. It supports a wide range of guest operating systems including Windows®, Linux®, Solaris®, and various versions of the BSD operating systems.