Your low CPU speed (lower than minimum requirements) is the likely cause of your slow frame rates. The aerodynamics for FS One requires quite a bit of computing horsepower. Even though you have 1 GB RAM and an X1300, it is likley that your slow CPU cannot perform the needed calculations fast enough and keep the graphics card fully "fed" with a stream of polygons to draw. Also, if your front-side bus is slow, your performance will suffer even more.

Keep in mind that a fast graphics card needs a fast CPU, or else the graphics card will spend a lot of its time waiting for the CPU. With heavy computing, like FS One, the X1300 is likely waiting around most of the time for the CPU to finish math calculations. Aircraft with more advanced aerodynamics typically require more compute power -- it's a basic relationship. The Ultimate and Edge have very advanced aero and perform many more calculations than something with more simple aero, like the Alpha trainer. Propellers also require aero calculations and that is why an Alpha is slower (needs more math) than a jet (which doesn't need prop aero). Your numbers actually show the relationship between aero and number crunching for the aircraft.

You have what's called a CPU-choked situation. People with fast CPUs and slow graphics cards have a graphics-choked situation.

Basically, to solve this, you need more compute power. Try reducing graphics settings, since these can also reduce (somewhat) general CPU load as well.

Also, try flying the Vigor heli and let us know your frame rate. Thanks.