RealSpectrum
a Sinclair - ZX / Spectrum / QL Series Emulator on the Windows/DOS platform
RealSpectrum is intended as a high-fidelity Spectrum emulator with no compromises. It reproduces the Spectrum hardware with a previousely unseen accuracy and it has been designed to support the most advanced features for the most realistic audiovisual experience. You will be using the closest thing to a real Spectrum machine :-)
Author's website: http://www.ramsoft.bbk.org/realspec.html