I think I found way around this...
Well, as you all know, you can't sell a game and use a majorly popular band(Disturbed, Rob Zombie, Marilyn Manson) without their consent to use the songs. Now, that the game is freeware, they can't sue me for cost of damage or lost money from inputting the songs into my game considering I'm not charging. They can however tell me/sue to not use their music in the game.
You know those really long license agreements that no one ever reads when you buy and install a game? Well, I thought about adding this:
By installing, playing, downloading, or using this game in any way, you agree that you do not hold myself or Manic Games responsible for any content in the game. You also agree that you will not hold myself or Manic Games for damages toward your computer, company, or anything else.
Heh, they agreed to it.