NSF to midi doesn't work for shit.
What are you trying to accomplish? If you're sampling NES tunes hoping to make a remix for OCR, don't, because OCR will reject you outright. If you wrote your own NSFs however, I'm assuming you probably did it in FT, and still have your FTMs. The best way is to load up your FTMs into FT, solo each track and export each track to wav, then load em up into your DAW.
If you don't have FTMs, you're likely stuck using a winamp plugin and winamp's disk writer output like Oinkness said. I do not recommend doing that though, because most (if not all) winamp NSF plugs have terrible timing and your head will explode trying to work around it.