It appears we have a thread almost full of thickos here, so I'll be blunt - in no way is emulation illegal. Proof? The fact that Nintendo uses the Virtual Console, Sony has the Emotion Engine chip, and Microsoft uses whatever the hell they use. Furthermore, were emulation illegal, then programs like ScummVM, DOSBox, WinUAE and the whole bloody lot would be illegal to download.
Depending on where you live, backing up your legitimate copies is not illegal. What is illegal, on the other hand, is downloading game files that are still covered under copyright law (and yes, that goes for abandonware as well).