Based on reports posted here, FlightGear 2.0.0 is having issues with installing on Windows 7. The installer hangs when trying to create directories in the default install path. Fortunately there is a way to counter that.
1. Create a folder in your personal folder (C:\Users\<username>)
2. Make sure there are NO SPACES in the directory. For me, I named it "flightgear" sans quotation marks.
3. Launch the installer.
4. When you get to the directory part, select the folder you created in your personal folder (repetitive innit?)
5. Everything else, as far as I know, can be left the same. The sole exception is Terrasync.
6. Installation should continue as it should.
7. ???
8. PROFIT! You installed FlightGear 2.0.0 on your Windows 7 PC and should be able to launch the simulator just fine.
This was tested on an Acer Aspire 4530-6823 notebook with the specs you see down there in my sig. Your mileage may vary.