GL-
How many years have you worked with Macs, it doesn't sound like it has been too long.
"Don't diss the Mac...hardware at least. The G4 can kill the PIII and Athlon with its pinky finger in terms of floating point performance now that it has one of the best implementations of a SIMD instruction set."
Wrong. When tasks are optimized for both SSE/3DNow! and Altivec the Mac comes out on top on average by about 40% on a MHZ-MHZ basis. x86 currently has a 100% edge. AltiVec as it stands now is a more extensive SIMD set and is capable of tasks that neither SSE nor 3DNow! are but as of yet applications that utilize it are far less then their PC alternateves.
In terms of overall FPU performance the G4 gets b!tch slapped hard by the Athlon and even the PIII has its' way with it. The only application that I've seen the G4 close in is Lightwave render times and that is only comparitively, the x86 chips still have a nearly 50% edge in terms of performance when ignoring clock speed.
"All the highend 3D apps are being ported to MacOS X. Why?"
No, only Maya has been announced recently as a port, and I haven't heard any current Maya users get too excited about it. Most of them will more then likely stick with either the Irix or NT ports. Irix for the best port, NT for bang for the buck.
No other high end 3D app has been announced recently as a port to OSX. Lightwave has been available on the Mac for as long as I can remember, none of the other PC/*nix titles have said jack about OSX.
"That's like saying the F1 circuit tracks aren't a good indicator of car performance because they're heavily optimized for F1 cars by having no potholes, little debris, and no traffic lights. Those tracks should be praised for creating an ideal environment for getting the most out of the F1 cars. I'm only sorry that because of legacy x86, the P3 and Athlon have to deal with all of these potholes, debris and red lights. Let's give credit where credit is due. Motorola made one fine chip around one very good platform. And it is indeed faster, clock for clock than x86 chips."
Have you ever used Photoshop on the PC? You assign memory in the application, running Windows. To say PS is poorly ported is an understatement. I think it still is a perfectly valid benchmark as PS performance is important for many users but it is not a well ported piece of software. Let's use something like Bryce or Lightwave, something that was done properly.
Motorola most certainly did not build the 7400 around the Mac platform. It is designed for embedded devices as its' primary objective, the reasons for the lack of MHZ. Moto made a design decission in the way they designed the processor to make it very fast at low operating frequencies in comparitive terms due to this fact. If they were focusing on the desktop market they would hve had sense to realize that people care, a lot, about the number on the box(MHZ). Apple was foolish relying on Moto simply because they had AltiVec, IBM has demonstrated PPC chips using the G3 technology that blow away the G4 in all non AltiVec enabled tasks(clocking in the 700MHZ range), so roughly 95%. Apple wanted PR instead of looking out for what is best for their customers.
"The mac version of the Rage 128 is clocked slower than the PC version if I'm not mistaken (I tried to verify this but ATI doesn't post these sort of specs...at least for Macs)."
Back in late '98 early '99 they were. This was an issue with the first revision of the G3 Macs. At the time if people remember the Rage128 had yet to start shipping on the PC side, the reason for this was massive yield problems. Apple needed the boards badly to launch their new G3(the blue and white ones) and told ATi to give them whatever they had(paraphrasing). ATi could supply in volume Rage128 chips clocked roughly 50% lower then what would be launched on the PC side and Apple took them. When ATi had their problems fixed they shipped the full speed Rage128 boards to Apple and they were included in all RevB G3 towers. If you have one around you can identify them by heatsinks, the RevA towers didn't have one on the graphcs card while the RevB and on did.
This in itself wouldn't be too bad but Mr. Reality Distortion Zone sent out "cooked" press units that contained boards running at full speed to all the review sites/mags and also posted benchmarks using the non castrated Rage128 chip on Apple's web site.
I'm not trying to bash Macs here, but you seem to have gotten a lot of disinformation from somewhere. People use Macs for two reasons, they like the GUI(which is only a small part of the OS) or they work with images that need to be accurate when they are sent to the print house and come back.