I'm partial to the freeware program, Fractal Explorer. It is definately among the best--if not the best--of the freeware fractal programs available. As the programmers don't speak English very well, they have paid particular attention to ease of use. There are now 'mouse over' context help for almost every feature. New versions, including Betas, are avalable rather frequently, always adding new features. It makes available literally hundreds of established formulas, some 55 Sterling equations and supports user defined formulas. It also supports IFS constuctors, 3D attractors and Quaternations as well. At the price, it's definitely worth a try. The URL to the home site is: www.eclectasy.com/Fractal-Explorer/index.html. Just my 2,000 cents (adjusted for inflation. :)).