It's against forum rules to share rom links (legal issues). But I will further clarify what FireFoxx has stated.
First and foremost, for emulators you can visit our homepage and in the top left corner click on brewpacks. There, you can download most emulators.
NES~ Look for NesterJ. I think the latest release is version 1.20 alpha or something. It will play nearly all NES games without a hitch.
SNES~ look for snes9x tyl 4.2.0 I think it is. It will play about 98% of SNES games but around 20% may have slight speed issues. Some can be fixed pretty nicely though.
N64~ Look for Daedalus R10. R11 will be out "soon" also and will address compatibility issues. This emulator is still very much in development and most games either don't play or play very slowly. Games like Mario 64 and Super Mario Kart - given slight tweaks, can be played at nearly full speed and are quite fun to play
GBA~ look for gpsp09. This emulator will play about 92% of all GBA games perfectly. The emulator lacks more advanced features, but still has all the main functions you'd expect out of an emulator. The author has primarily been working on bug fixes for certain roms to work instead of working diligently on adding more advanced features.
*edit*
I'm just going to move this to the Help section for now.
-DarkPacMan77-