it can achieve much better results when performing pure integer math.
No. The altivec is used for vector operations, not integer. Here, read this comparison of both processors:
G4 versus k7
When is comes to 128-bit vector calculations, the G4 is a damned fast processor. The altivec is what allows the G4 (and therefore all current powerpc towers) to achieve workstation-level performance
for certain, specially-designed apps. The athlon, on the other hand, kills the G4 in integer and floating point calculations (which is what windows-native programs require, including games). According to this article, which I have no reason to doubt (lay off mac fanboys, he actually prefers the G4), the original K7 simply has more brute force than the G4, with 9 fully-pipelined functional units, as opposed to 6 on the motorola chip. Also note that both processors are "post-RISC", not RISC or CISC. The athlon actually emulates the x86 ISA, effectively changing the x86 instructions before processing them. Ultimately, both CPUs are very good at what they do, they just do different things.
OSX wouldn`t run nearly as well on AMD hardware as it does on the G4 due to a lack of a good vector FU. The athlon, for example, must use two of its three FPUs to do vector calculations, enabling it to caculate 64-bit vectors, as opposed to the 128-bit per cycle provided by altivec. OSX's pretty interface (and fast operation on higher-end macs) is a result of the optimizations made available by the altivec. 3DNow, MMX and SSE simply can't compete with the Velocity Engine.
For obvious reasons, PC apps and games are optimized for fast FP and integer performance, which is why so many of them run slower on macs, whereas mac apps (eg. quicktime) run better on the G4.
As to why apple doesn't open it's market. It's not just about being a niche. By keeping all hardware and software under one roof, they are able to to ensure that the two mesh together to form as cohesive a system as possible. You don't have as many bugs, and those that you have are easier to fix. Imagine Microsoft, AMD (or Intel), IBM, Klipsch, Logitech, Maxtor, etc... all working in one building making sure that all their products function perfectly together. That's *kinda* what you get when you buy a mac. All too often on PCs we have a product X that won't won't install because product Y is causing a conflict with product Z...and so on. While for the members of this forum these kind of problems are fixed rather quickly
, some people don't want to put up with that.
But PCs
are cheaper, and more familiar, and so they sell. For others, the options and customizability available on PCs are what convince them to buy. For me, it's both. Just like the processors that power them, PCs and Macs cater to different needs, and both play important roles in the computer industry as a whole.