First, unpack the file you downloaded (extract folders:yes).

The solar system is pretty large which might be taxing your system too much.
Therefore I have splitted it up into several parts, usually containing a planet and its moons.
The folder \Demo.OrionArm contains several batch files, that you may use to go to a certain planet of the solar system.
for example: 20090818_CW_FICTIONAL_DWARF_PLANET_GROUP.bat
runs the demo with the system specified.

Usage

The program needs some time until the scene is loaded. This can take between some seconds and a minute.
Once the program is loaded you will always look at the sun. Press the left mouse button once to go to the next object.
You can then press the mouse button to cycle from planet to planet and use WASD to move around

Available keys:

W,A,S,D = use keys to move/fly in space
Left Mouse Button = goto next planet
Right Mouse Button = goto previous planet
Mouse = look around
F = hide UI
R = Toggle Render Mode
Print = Take Screenshot
Esc = Quit
NEW in v2.1:

Troubleshooting

If you get an error message about missing application configuration, run the Microsoft Visual C++ Runtime: vcredist_x86-sp1.exe

This demo runs at a constant 60fps on my test system (Core2 3Ghz, 4GB RAM, ATI 4850 w. 1GB VRAM).
However this version is optimized for best quality and may run slower on less powerful systems, especially those with little Video RAM (128Mb).
If you have problems with fps or jerky behavior, PLEASE contact me with details of your system and the problems encountered.
This information will help me to create a version that is optimized for performance, and should not look much worse.

Tips

You may find that the camera moves too slow. You can change this and a number of other parameters in a text file.
Open: bin/release/DwgTest.cfg

Some of the parameters that you may change:

MoveConstant=5     //value controls how fast the camera moves.
You can set MoveConstant to much higher values if you want.

MeshLod=1     // meshlod reduction
If you set this to MeshLod=0 the program loads more than twice as fast, but the quality of shadows is reduced, and you get less fps.

ShadowTechnique=SHADOWTYPE_STENCIL_ADDITIVE     //Shadow technique used
Set this to ShadowTechnique=SHADOWTYPE_TEXTURE_MODULATIVE if you want to see a drastic increase in fps.
It will however disable object to object shadows.