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,