Mupen64Plus - Windows
Mupen64Plus is a cross-platform plugin-based N64 emulator which is capable of accurately playing many games. Included are four MIPS R4300 CPU emulators, with dynamic recompilers for 32-bit x86 and 64-bit amd64 systems, and necessary plugins for audio, graphical rendering (RDP), signal co-processor (RSP), and input.
Mupen64Plus is a command line program but drag and drop works well.
If you are more comfortable with a GUI several frontends can be found here.
* Dynamic recompilers for 32-bit (x86) and 64-bit (amd64) machines
* OpenGL video plugin, with Hi-resolution texture support
* LIRC Infrared remote control support
* Rumble Pak support (Linux only)
* Cheat system with gameshark code support
* Speed adjustment with smooth sound output
* Shared library interface for integration into other systems (front-ends)
* Command-line Front-end application