Lol, yeah, all of the above plus the little legal technicallity! Unlikely it'll ever be enforced, but from a legal point of view, emulators are only supposed to be used for the following two scenarios:
1. As a backup to a game you already legally own on Cartriage
2. As a demonstration before purchasing the game legally - in this scenario, it's only legal to download the game for a maximum period of either 24 or 48 hours (can't remember which!) before it should be deleted!
Well, that's the legal standpoint anyway - actually downloading loads of games for an emulator and keeping them is rather bizzarly against the law!
Of course, nobody actually takes notice of it (I have nesticle, as well as emulators for the snes, sms & megadrive/genesis) - but that's mainly because it's a law that's never enforced! But you never know - there's always a first case......