There seems to be a bit of confusion about emulation. Emulators are completely legal. Stop harrassing people when they post about them. They're fine. Don't harrass about how the poster obtained the ROMs, it's none of your business.
Now the reason I'm making this is because there is confusion about obtaining ROMs. You can obtain a ROM in any way if it's abandonware (the company isn't making money from the product), so that's just fine and dandy, but be careful about the credibility of whatever site it is on. I've seen sites which have illegal downloads that were labled abandonware. But downloading other ROMs however, is illegal no matter what. Even if you own the game, it's illegal. You must rip the ROM yourself from the physical copy. Most people can't do this. But you may be able to get a license for the game to use on an emulator from the publisher or developer, if I'm not mistaken.