I've found that some NES emulators don't handle some roms well. (For example, you couldn't beat Legacy of the Wizard since the final battle would result in Keela the Dragon constantly depleting your life until you died...thus, you couldn't complete the game.) However, using a specific emulator, I been able to get most roms to work, like Castlevania III which some emulators I had couldn't handle. I'd mention the emulator name but I am not sure if that'd break any rules...
Anyhow, I need to get my mitts on those pirated roms! I only knew where to get one, so I'll have to do some searching for the rest.