ali: An SSE2 emulator is just a program that will.. ermm.. emulate SSE2.

There are a few ways to do it:

* Go through ALL the assembly and replace SSE2 with code that's equivelant, but isn't SSE2.
* Wait for invalid instructions to be hit (which should cause an exception/whatever your CPU wants to call it), then emulate them if they're SSE2. (I'm not sure this would work on x86.. but certainly it's a way of emulating instructions)
* 'Virtual machine': read the program and emulate all the instructions, updating it inside virtual machine (so change to eax register doesn't necesarily change eax register on real machine (it still could!)).

As far as finding one? Sorry, no idea. QEMU might do SSE2, but I doubt it... I think it just does PII.