Vampent.com today published a perfect NES emulator for Series 60 including N-Gage. It is the first emulator on N-Gage ever that has perfect sound effects the same as PC emulators. It runs smoothly and support more than 90% mappers. It is a commercial software, but it hasn't many limitations as other softwares. Vampent.com also provide lifetime upgrade to registered users.
Take a look at http://vampent.com/