Windows is popular and look what a cesspool that is.

I have a couple concerns right off the bat.

Registers - PPC has a boatload of registers. x86 as I understand it (not particularly well) doesn't seem to have enough and pays for it.

Endianism - I don't want to deal with swapping bytes around going in and out of sockets. I've got a boatload of old code that assumes that the machine and the wire match and I have no interest in fucking around with byteswapping.

Altivec - there's an awful lot of audio code that relies on this stuff. What will be the equivalent? How long will we have to fondle ourselves waiting for efficient ports of pro-apps (audio, video, etc)?