Server:os-windows is an additional function group, to house those checks that we think should apply to /every/ windows server, no matter what it's doing. The checks it performs are: 

• "needs reboot"  checked every 90 minutes.
• "windows updates" checked every 720 minutes (12 hours).
• "antivirus" checked every 30 minutes.
• "load" checked every 30 minutes
• "drive space" checked every 15 minutes
• "ping" checked every 15 minutes