Thanks for the plug, Tres. :-) I love quaternions, but they are indeed demanding. It takes me a lot of time to get what I want, then, because they are 3D instead of 2D, they take a long time to render. Having said that, let me say I'm talking about maybe 15 to 30 minutes on my 2.6 HHz Northwood, while I typically render a big complicate XD image overnight. So render time shouldn't be a deciding factor. As far as ease of use, right now QuaSZ is easier than FE. But Arthur is working on a new version, and the quat generator will definitely be improved. And of course, FE is freeware. I think, as with any art, it comes down to doing what you like. Feel free to send me an IM or email if you'd like to discuss either QuaSZ or FE further. Check out the galleries at http://hypercomplex.org/fractals.htm The URL for QuaSZ is http://mysticfractal.com/ for FE it's http://www.eclectasy.com/Fractal-Explorer/