The emulator is part of the SDK intended for developers. Look on the MSDN site. But, as such, it is not as simple to set-up and use as an emulator available for general use on a PPC e.g No official MS GAPI available (although there is a workaround), etc. But if you were planning to get it for playing PQ2, wouldn't it be better to just play the x86 version?
As powerful & optimised as DieselEngine is, I doubt there is any major performance to be gained from implementing it with PQ2, in fact it may even become slower! What i do like about DieselEngine is it's similarity to many DirectX functions, but it's apparently pricey. PQ2's performance is more due to the relatively weak cpu, not really the inefficiency of the code. Send him a copy though, i suppose he has nothing to lose! (apart from time & energy

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