I fondly remember Nesticle as one of the first emulators I ever tried. Back in those days (1997) it was already able to play many NES games properly and fast, even on the poor hardware I had at the time (a 486).
It may have a funny name and a weird mouse cursor, this emulator is what revolutionized the world of emulation back in it's time. Unfortunately after part of the Nesticle source was leaked it was discontinued, but it still remains one of the best NES emulators currently available.
The latest version of Nesticle is X.XX, but is for DOS only. The latest Windows version is included with version 0.42. The DOS versions of Nesticle require the memory extender DOS/4GW to run. Just extract this file into the same directory as Nesticle. You won't need DOS/4GW for the Windows version of Nesticle.