Mac OS X on Xbox 360
github.com
github.com
The issue with the Wii version was it running in 88MB of RAM, at least with 512MB on X360 this is actually in the ball park of usable. It also doesn't say if it uses multiple cores or not, but even with a single core it should be fine even with in-order execution.
For as awesome as Tiger was, it was RAM heavy compared with Windows XP at the time. 512MB really felt like a minimum to getting it running well, and 1GB if it really wanted to fly.
I think that’s because XP is mostly 2K with a new theme engine and some consumer stuff bolted on. It didn’t have full alpha desktop compositing and high resolution icons and other such things.
The closest Windows analogue to 10.4 is probably late-lifecycle Vista (after all the stability and hardware issues had been sorted) or 7, which are much closer in terms of features and modernness and were similarly heavy.
The AltiVec requirement is odd - I’m sure I remember running Leopard on my G3 by tweaking with a file on the installation CD and allowing it to install on my iMac.