Fractal number cruncher - most efficient hardware to do the job?

Which would be choice of hardware would be best for a machine to produce fractals and fractals zooms? I would be grateful for advice from somene who really knows. Would it be i7 processor(s) or multiple earlier dual/quad core processors, say a server board with raid? If someone can discuss with me what are the best options I would be very grateful. The end result would be fractal zoom movies at 4200 x 4200 pixels, projected onto a 10 metre digital dome. Quite a big order. Thanks.