Oooof bit warm in here *puts on flame proof jacket*
I personally don't see the issue with the CPU being dual core (or whatever) and OS4 not supporting multi-threading. This is normal, the CPU comes first, the OS makes the best of the features of the highest end hardware capable of running said OS. 64bit CPUs came before 64bit Windows (which was a disaster in the case of XP64 btw so they can hardly make a worse job of it)
So in essence we have a G5 PowerPC unit? I mean in terms of CPU power ghz per ghz. The reason Apple left PPC for Intel was simple, laptops. The G5 was never going to make it into the laptop market and Apple are not stupid, laptop sales in the middle of the last decade were on the up and up and a very desirable piece of tech....exactly the kind of thing Apple thrives on. There's nothing wrong with the G5 CPU for desktops. Also my only issue with x1000 is value for money, if it was 600 dollars and included a capable GPU then great I would have zero problems with it.
PS I'm not totally up on side lines or older PPC stuff, Cell is where it's at (and Xenon if IBM were clever enough not to be screwed by a Microsoft exclusivity contract of course) so that was a genuine question about the relative sophistication of the x1000 CPU mooted at in this thread.