FamiTracker is also a good choice for NES style music. It's not as accurate as Deflemask but a little less difficult to learn.
You can even write accurate GB music in FamiTracker if you know what you're doing - by exporting a specially formatted NSF and running it through this script. http://forums.famitracker.com/viewtopic.php?t=1834
Might be a little too complex for newbies, though.