They're called REALLY REALLY fast machines w/ gobs of video ram (faster update of the screen), gobs of system RAM (faster updates when you are making the scene and general ease of use) and a super horrendously fast processor (Athlon 1000 MHz is really nice ... One of the PCMAG test benchmarks was a Bryce scene and it was 10% faster than a like setup/speed PIII) Not to mention a super fast hd (10k RPM) w/ lotsa room. At least, for a PC. A Mac on the other hand, a 450MHz G4 with Gobs and gobs of RAM (most allocated to Bryce) would be REALLY nice ... :) Other wise, make the scene is several parts, render of multiple computers (each running Bryce) and then composite in an app like Photoshop ... :P An SGI running NT, would be nice as well. Any one of these will cost upwards of $2500 for the PC, about the same (I think, haven't priced them recently) for the Mac, and upwards of $5000 (min) for the SGI. Enjoy!