Regarding questions about OS Compatibility for CBO v 4.26, the following is taken from Comodo’s Download page for CBO.
Windows For Workgroups 3.11 (Win32s required) Windows 95, 95A, 95B, 95C (Winsock 2 required) Windows 98, 98SE Windows ME Windows NT4 (SP2+ required) Windows 2000 Windows Server 2003 Windows XP (any, including 64) Windows Longhorn Server Windows Vista (any, including 64)