Well that isn't what I've seen, x86 chips struggle to decode hi def h264 1080p content without hardware acceleration. PowerPC's handle it much better.

I was surprised to see that the nVIDIA 6 series chips were planned on being supported. I now find it is only the lower end cards. :x That cannot be because the high end chips can do it as they cannot unless supported by the driver. Acceleration helps the CPU in all cases.