What software did you use to make this? If you don't mind me asking :)
i use sonar (cakewalk) to actually make it out, but i used VSTs that emulate PSG and noise, one of which is a replica of the NES/FAMICOM soundchip.
dreamstation dxi (all manners of instruments and effects)
triforce (NES synth device)
toad (for various percussion things)
famisynth (awesome soundset with built in parameters you can play with)
in general, i only replicate the sound, not necessarily the methods an NES would follow to create the sounds, but i did follow all the rules in the end.