Instructions
Navigate to the DeSmuME website and click the download link for the latest version of the emulator. As of September 2011, it is version 0.9.7.
Right click the downloaded file and select "Extract All" to unzip the contents of the archive to your hard drive. Double-click the "DeSmuME" executable file (.exe) to start the emulator.
Click "File" and "Open Rom." Navigate to the folder where your "Golden Sun" ROM is, and double-click the file. If you have the original game cartridge, but not the ROM, you can download it from sites such as FULLROM.
Click "Config" from the file menu and select "Sound Settings." Click the check box next to "Advance SPU Logic." Click the radio button next to "Synchronous" under "Synchronization Mode."
Click the radio button next to "Synch Method Z" under "Synchronization Method." Without changing these sound options, the game sound effects will be badly distorted. If you find the game runs too slowly after changing these settings, click "Emulation" and "Shut Up" to turn off all sound effects. This will leave only the background music but the game will run faster.
Click "Config" and "Frame Skip." Click "Auto Minimize Skipping" and, depending on the speed of your PC, select the amount of frames that the emulator can skip. "0" (never skip) will skip no frames but will cause a slowdown if your PC is not fast enough. Click on a frameskip option and then check if your game is still playable until you find a suitable setting for your setup.