I don't have the cash to stump up for a PS3 or 360 devkit, but the G3, G4 and G5 macs are running with PowerPC chips, which I believe is virtually the same architecture as the 360, and only missing the SPUs from the PS3, so I would like to know which Macs would be good for profiling code with.

I'm after a machine that would give me equivalent timings (not actual timings, but scale the same given difference code) so I'm looking for ones that have about the same cache size and memory bandwidth ratios as the consoles. Are there any specific Macs that have these traits?

The reason I need one is that I'm developing a new programming language for games development that specifically targets the current and potential future of console hardware. One aspect of this is the in-order microcode expanding risc chips at the core of both the 360 and the PS3, and probably the next generation too, which is why I want a PPC based mac, as I'd heard that places like where I work used to use Macs as pretend 360 devkits until the hardware design was in a fit state to send out prototype 360s.

At a later date, I'll want to get my hands on an FPGA (as that's the only other route I can see consoles heading any time soon), and a cluster (as they are good practice for ensuring your task scheduling and separation are up to scratch), but for now I just need to know if there is a sweetspot machine that had very similar specs to the current consoles' CPU and memory bandwidth.