Here's a brilliant idea,
Go find a used NES and Zelda off ebay for a few bucks and let your nephew play the game like it was originally intended.
I looked at them, but wasn't sure if it would be reliable or if the cartridge used a battery.
He actually asked for an original NES with the stupid friggin' robot. (Both it and the zapper wouldn't work without a CRT TV anyway).
Based on prior gifts he couldn't live without though, there's a 80% chance he'd play it for a week, decide the graphics suck and the games are too hard, then never turn it on again. USB gamepads and an evening spent configuring are all I'm willing to invest at this point.
I browsed the emulators mentioned, but the only ones I ended up play testing were fceux and virtuanes. Both have their quirks. Howard's add on interface for fceux is nice to have, but the sound quality sucks compared to virtuanes. fceux also has some flickering that isn't present on virtuanes. VirtuaNES just looks and sounds better. Only issue I had with it was that it nagged me about the headers on my roms being incorrect. Tried a different set and have only been nagged once now.
Pretty much done now. I made a separate gamelist of 34 favorites so he doesn't get discouraged by launching too many crappy ones.
Might add some instructions to the lower left.