I have a problem on my PC (Windows 7 Home, Asus graphics card with NVidia GTX260 chip onboard). My primary monitor is Samsung F2380 (name in Windows is 'Samsung SyncMaster'). The monitor is connected using DVI on connector nearer to motherboard. When only monitor is connected than Windows assigns it #1 and its marked as main display. When I connect TV (name in Windows is 'SONY TV') using HDMI things are changed. Now TV is #1. My monitor remains main display but Win+P ignore its. As projector is used #2, as computer #1.
There is other situation when its terrible. Some games (for example BadCompany2) displaying picture to #1. So I must disable TV before I start play and after play I must turn it on back.
I think its bug in Windows 7.