Project64 is the best N64 emulator available, but it only runs on Windows. They stopped development last year, because almost all games work. Fortunately they also released source code for the trickier parts of the system. I suspect that this code is being used in the new (as yet unreleased) version of Sixtyforce, because it seems to be a big leap, and is the first update since PJ64 released their code. This is all just a guess though, but I hope it's true!