Use DeSmuME. Make sure you've enabled 'Advanced Bus Level Timing' in Emulation options, otherwise the game won't run. It's usually preferable to use the SoftRasterizer graphics rendering rather than OpenGL. Use 0-2 frameskips depending on how fast your computer is. 'Auto-minimize skipping' should be enabled as well.
One ast thing: make sure you're using the latest version of the emulator.