You can download either NESticle for DOS or NESticle for Windows 95 they are both the best nes emulator. Note: The DOS version comes with dos4gw.exe

or choose one of these:

Nintendo

NESticle	NESticle for DOS vx.xx released 8/19/1998
loopynes	loopynes for DOS v.51 released 8/24/1998
BioNES	BioNES for Win9x v.2 released 8/5/1998