I use TightVNC, which is free. When you log into a machine with it, the system tray icon goes from white to black, but on Win 7 you can configure that icon to remain hidden so anyone looking at the screen isn't aware someone's connected with VNC.
Also, set one password for normal remote access and another one for view-only access, that way you can remotely view the screen but there's no risk of accidentally moving your mouse and alerting the person sitting in front of the laptop that you are connected.