Quote - I also think that photomatix can create HDRI from a single RAW file, but I haven't tried that either.

As it's on the other computer, cannot really check but IIRC, no. A single RAW image has only 14 bits at most. What you can do is create multiple exposures from a single RAW image in Photoshop with the free ACR plugin (Adobe Camera RAW). Just develop them differently and save each as a different JPEG or TIFF. And then combine them in Photomatix. When you try to do that in Photoshop, it will say there's not enough dynamic range to create a HDR.

-- erlik