First, I should say that the secondary monitor is a 19-inch TV that only has HDMI inputs. My laptop only supports VGA output, so I have a VGA cable connected to a VGA-to-HDMI adapter, with an HDMI cable going into the TV. This setup works fine in Windows 7.
However, in Ubuntu 11.04 Classic, when I go to System --> Preferences --> Monitors, a secondary monitor is not recognized.
My graphics card is a 512 MB NVIDIA NVS 3100m.