Al,
You were right - but I made a mistake when I first tried to implement your fix.
I spent some time changing the power settings and choosing the preset menu for "maximum performance" and making sure that the sleep and hibernate features etc were all disabled.
As I mentiioned, things seemed better. But today was the worst sputtering and popping ever, despite "maximum performnance" power settings.
In the end - and you also mentioned this - the real culprit seems to be not the various sleep and hibernation options, but primarily the "throttling" of the CPU which is only found buried in the "advanced power settings."
So when the CPU options are expanded and set to minimum performance = 100 - that seemed to - at last - solve the problem, at least for now. It was otherwise unlistenable much of the time.
I will be curious to see if changing the CPU setting ONLY, while otherwise allowing the machine to sleep, hibernate etc might also work.
Thanks again and I hope this helps other Windows 7 64 bit users.