I'm not talking about Xbox or Gamecube or even N64 roms, I'm talking about really old stuff like C64 and Amiga games roms.
Anyway, I think roms is a great way to preserve old games and to give younger people a great opportunity to experience the great games of the past. It's also good for us older people as it's very fun to play those games you loved as a kid.. there will always be something special about those games for me.
Downloading roms is illegal if they have not been released as freeware. I think that downloading illegal roms is perfectly ok as long as you buy the games if they are ever re-released.
If you do that, then I really think it's a good thing.
I'm not saying I have any roms though, I'm just saying I don't have anything against downloading old roms (especially if the games are for systems that no longer exists and most likely will never be made again).
If companies are cool enough to re-release their old games however.. like Nintendo will be doing now with the Revolution, then I think downloading those roms is wrong unless you also buy them all once they're released.
There are some great games released as freeware though (for example, you can download many of the old Cinemaware Amiga games on their homepage for free).