Is Manage is a value which show if the computer is managed or unmanaged.
If the IS manage value is 0 there is a possibility that the computer has the agent installed but not manage (This happens when computer is not turned ON for long time and Purging Maintanance has set to retire the computer)
As of Now you can find Default reports
1. All Windows 2000/XP/2003/Vista/2008/7 Computers with no Agent
Reports-->All Reports-->Notification Server Management-->Agent-->All Windows 2000/XP/2003/Vista/2008/7 Computers with no Agent
2. Computers with Agent Installed
Reports-->All Reports-->Notification Server Management-->Agent-->Computers with Agent Installed