I've tested two Genesis/Mega Drive emulators, PicoDS and jEnesisDS 0.5. Both have their similarities but only one had the larger set of advantages. Both emulators run without sound and while both CAN run whatever I've thrown at them, jEnesisDS is faster,smoother and has a way nicer user interface. Kind of like comparing a European supermodel to one of those local race queens and the supermodel has some brains to boot.
I'll be writting a more in-depth review in the future but for the moment, get jEnesisDS 0.5 at DCEmu. Registration is required, but free.