Windows or mac?

I'm planning to use the psychotoolbox to show stimuli during vision experiments. The stimuli will mostly consist of video sequences currently displayed using standard video (.avi) players.
I played around with the windows version of the toolbox but encountered many errors, even from basic functions.
Regarding the fact thatI would like to have a system running reliably soon I have the following questions:

*What do experienced users recoomend: Going for the Windows
version and hoping for better software in the next time or
using a mac?

*Showing full screen videos, what are the important parameters
and limitations? I'm not experienced with mac's so could anyone give me some numbers like how many fps one can reach, what resolution, how large (kbytes) individual frames can be? And what do I need to know when buying an mac and especially the graphics card?


Thanks

Christoph Kayser