This is the most common hurdle. When you plug in your Parashara Light USB dongle, Windows 7 64-bit will show a popup:
Sometimes, Windows prevents older applications from running code in system memory areas. parashara light 70 for windows 7 64 bit install
This is the most common hurdle for 64-bit users. The drivers included on the original CD are likely 32-bit. Do plug in your USB dongle yet. This is the most common hurdle