As The Man (Aaron) said in a previous post, anything with a melody can be 'music'. Other than that, it comes down to a matter of opinion, really.

I've really come to love anything metal (death, industrial, etc.) in the last few years. In my opinion, anything that doesn't come close to rocking hard is mellow, and nothing I would listen to regularly. Of course, people are as varied in tastes of music as they are varied in personalities. Each person should like what they like.

Anyone who thinks someone else is inferior due to something like musical tastes is just shallow, and not worth hanging out with. Musical taste should be last thing that matters when it comes to who you hang out with, who you become friends with, etc. Seriously, what does it matter, anyway.