Are you sure you have a Intel HD card? On most netbooks (with Windows 7), NVidia has a feature called "Optimus Technology", which is meant to increase battery life, by automatically switching of the powerfull graphics card when it's not needed. However, FlightGear needs it all the time, even if Optimus says it doesn't. This miscommunication results in low framerates (because your computer will run Flightgear on the weak onboard processor).
To make use of the powerful graphics card, perform the following steps:
1. Go to the NVidia control panel. Probably located in the Windows Control Panel.
2. On the 3D Settings tab, you'll find a "Prefered graphics processor" option. Set it to NVidia.