I'll bet ten bucks that it'll be out looooong before PS2 and GC emus. Even though its different, its the same CPU, and therefore the same underlying codebase. Not having to emulate the CPU opcodes will defintely help. Its the GF3 thats the problem, but I'm sure it can be worked around.
Someone would basically have to strip the HAL from the Win2k kernel, make up for a few hardware differences, but in the end I imagine itll be a ton easier than emulating anything else.
Of course this is assuming youre running a P3 and a GF3.