I believe that both programs list both recommended and bare bones minimum requirements for available disk space, RAM, processer speed and graphics card for the programs to run properly. That information should be available on the Horizon and Great Planes websites. You can then compare that to your actual hardware setup on your computer.

If you're not sure of your exact set up, you can find it by going to Control Panel, System. Processer speed and RAM will be listed on the "General" tab. For information on your video card go to the "Device Manager" tab, and look for the video card line.

I'm not sure about this, but my guess is that the demo versions have fairly limited functions and will probably not give you a very accurate picture of how the full program will run on your box.

In addition, once you have installed the program, you have the option to disable some of the more graphics intensive features to speed things up a bit if performance is marginal.

Good luck.