Double-Take is licensed per machine and is available for the following operating systems:

• Windows 2003
  Certified for Windows 2003 Standard Edition and Enterprise Edition
• Windows 2000/NT
  Supports Windows NT 4.0, Server, Enterprise Edition and Terminal Server Edition and Windows 2000, Server and Advanced Server and Windows Powered Applications.
• Windows 2000 DataCenter Server
  Supports Windows NT 2000 DataCenter

The Double-Take Management Console can be run on Windows 98, Windows NT 4.0, or Windows 2000/2003.