VMware Workstation is powerful desktop virtualization software for software
developers/testers and enterprise IT professionals that runs multiple
operating systems simultaneously on a single PC. Users can run Windows,
Linux, NetWare, or Solaris x86 in fully networked, portable virtual
machines - no rebooting or hard drive partitioning required. VMware
Workstation delivers excellent performance and advanced features such as
memory optimization and the ability to manage multi-tier configurations and
multiple snapshots.

http://www.vmware.com