Not familiar with Nividia, but can you export out as a PNG or JPG? If
you can do that you can put the files into your Textures folder in
Fireworks and they'll show right up. Note that you should make the image
dimensions 128 X 128 or 256 X 256 to be compatible with FW textures.
author, Beginner's Guides to Dreamweaver and Fireworks
Extending Knowledge, Daily
Team Macromedia Volunteer for Fireworks: http://www.macromedia.com/go/team