Is ROMs legal?

Hi all,
    I have asked myself this question years ago, Is ROMs legal.  I even went to check it out
on the internet, I remember the site being rom nation or a very similar site to this,

On the site from what I can remember, of what I have read that It was a downloadable file (could even be) and used/needed a file to run. 

How do I go about find these answers and I am now purchasing games to play, on Playstation 3 which I'm trying not to play and PC.  PC is different.  I have many games that are ROMs, tho my self thought
is that they are not a legit as they say.  So they are in a B O X to be disposed of if needed to be. By the LAW (aka. LINSANE@!-_)

This is the game that I want to purchase by the way and I'm not going to get a DREAMCAST