The fire demo only fills the bottom of the screen. It doesn't fill the entire window. On 3 of my test machines it runs at 60 fps. Even if it is running slow, it should still work, just the flames will be more choppy than expected. I did want to make sure you knew that the entire window is not filled up with fire. In fact, probably just the bottom 1/4 of the screen is. The code on the CD is how I intended the effect to work. If your results are matching the CD, then it is working as expected (minus the slower fps due to the GPU).
Hope this information helps,
Chad