why not slap a 700MHz P3 (since you cant get a P4 that slow) against a 700MHz G3 and then see how much "better" your beloved x86 is.
Well the c't (germanys leading IT-magazine) did just that !
Actually they took a P3 and G4 at 1ghz and ran some benches
on them. Both sides were compiled with GCC and they P3
showed slighly better results (~ 10-20%).
A AthlonXP would be even faster a 1ghz (real clock).
You may put some blame on the gcc, but then its the only option
for COS4-SW (atleast if you don't want to start on ASM again).
Altivec may also have added to a better result, but that would
need heavy work on the sources and some SW simply can't
make use off it no matter what you do.
Almost forgot: The A1 doesn't have Altivec :-o
PPC is good when you need:
Low power-consumption.
Low heating.
Long life in hard envoirements
If you want number-crunching-power x86 is the only option.
Will this change with G5 vs AMD-64 ?
Don't know but i have some serious doubts on it.