When looking for a good DS emulator or more precisely for the best DS Lite emulator out there that can play commercial nds roms (that is the games from the store) and all the home made stuff from the net I had a hard time at first, but than I ound thses 4 sites and now I can tell you that No$GBA is the best followed by DeSmuME and Ensata (from Nintendo)

» NoGBA download site
» DeSmuME home page
» DS emulators compared
» NDS emu.com ( DSemu – was first emulator )