Yeah, it's impossible to not ever argue.. some people can even make it seem cute, lol (okay, the Korean dramas, ha ha)
You have to find out if you are compatible in the really important things, like your view of a future together, view of money and any kids later on, reponsibilities (who does what in the house, in relationship) What kind of person s/he is.. Integrity, keeping promises, etc. Who does the cooking etc.
That is, if you wish a steady, long-term relationship.
Music is only a problem if neither of you can ever wear headphones, or if you 'must' listen to it together (if this is your perfect view of relationship)
Everyone has deal breakers, and if music is really important, maybe some music may be a no-no, some 'negotiable' etc. I like some pretty silly music too, and some really cool too.. So it depends. If someone only wanted to listen to depressing music all the time, or only to polka (or techno/house - yikes!), that would be a no no.
I really love what Chola wrote though. If everyone always agreed on everything, it could be pretty boring.. Besides, you may inspire her to like some of your music too.. Never expect it though. People change if they wish to, it's never to expect it, so if you like her as she is, then okay, if not, maybe it just wasn't meant to be... Sometimes you can tell a lot about a person through music taste, and sometimes it can be misleading.. I remember music taste was very important in high school, later on not so much anymore.. It would just be silly if music taste would be the only thing keeping you apart..