Can someone who has remote access to my computer tell if I have an external monitor attached? I have a Windows 7 computer.
Also would they be able to view what I have pulled up on my external monitor?
Yes, if remote viewer can see both the monitors. I take remote access for support and if the person has two monitors then we can see it. It only works if both are not set to mirror (the other one duplicating the first scree).
maybe in Remote Desktop Connection settings there is option Display configuration slider small to large (Full Screen)
Using Multiple Monitors in Remote Desktop Session
I mostly agree with Jan. You can definitely tell whether someone has an external screen, particulary if it's in "extended desktop" mode (since you can move the mouse off the main screen).
If the controlled PC is running Windows 8, TeamViewer, which is my remote-access software of choice, allows you to switch between the monitors. You don't have that choice with earlier versions of Windows, but as a remote access program, it's not difficult to reorganise the desktop, and I've done that on ocassion. Other remote access programs have different features, but the bottom line is you can't really use your second screeen to keep things private. You /can/ use it to make things more difficult for your support person...
They could definitely tell if you have an external monitor, projector or other display device attached. The display device has to be"hardware recognized" by your graphics card and the operating system to be used in the first place.
Whether they can actually see what you have open on that monitor depends on the type of remote access they have.
If it's full Remote Desktop/VNC access they should be able to see all your display devices and whats on them . If they "only" have a terminal access e.g. via telnet or SSH then they can see what is running on your system but in most cases can't tell which application or process is running on which display device.