For clarity's sake, it is perfectly legal to use an emulator (or even ROMs) if you have the official game. I emulate PS2 games on my PC too, but I use the original DVD, which means it's completely legal. Just so there's no misunderstandings 

This is why we don't want any discussion about emulators here, there are too many holes. Well, with the exception of DOSBox as it doesn't require any extra ROM of any sort and can be used to run games available for free from http://www.elderscrolls.com.
