So I buy a Commandos game and like it a lot. I now want to go multiplayer with my little bro cause I have 2 computers. Is it illegal for me to make a copy of the CD for my own use so I can play together? Would it not be like copying a music CD so I can listen to it in my car and my room? The Nero software that came with my DVD burner doesn't want to let me do that, so should I forget it.

Along the same lines, are drive emulators illegal as well? Like, if I can make ISOs of all my CDs and then just mount them into drives so I don't have to keep getting out all my CDs, is that fine? I don't want to be illegal or anything, I just want to know what the deal is with that.

It is not illegal to copy a game for backup purposes in the US, but it would be illegal to copy it for purposes of playing it in multiplayer mode.

is it illegal to store ISOs on your HDD? I wouldn't think so if they are for backups.

No, You can store the ISO as a backup. That's legal, though you'd have a hard time proving it was a backup. If you simply copied the CD once, that would be a backup, and you'd stand a chance of proving it too.

If however, you used a "backup" for the explicit purpose of playing multiplayer, in a game that that required a copy of the cd for each player, THAT would be illegal.