Wii Fanboy says: download it!
We love Castlevania. And the release of Castlevania III: Dracula's Curse is a welcome trip down memory lane. For the small sum of 500 Wii Points, we'd suggest you take the trip yourself and enjoy some classic Castlevania for the NES. There isn't any other way to enjoy it unless you actually have a working NES and the cartridge (or you want to play it on your PC).