iTunes problem

Hi everyone

I recently just bought one of the new macbook pros (first time mac user) and I just had a quick problem with iTunes.

I just added to my library 42 gigs of music from my old computer. I noticed that my hard drive was getting filled up pretty fast (at like 82 gigs by the end of it all) so I investigated and noticed that itunes had made copies of my whole library on the iTunes library music folder. So I deleted it all figuring that itunes was just making dumb copies for whatever reason. Now when I click a song on my itunes player it doesn't play it because it can't be found.

So I was wondering if there was some way to turn off this feature or wahtever. Cause I know on my PC (windows) itunes definitely did not make copies of every son I put in my library. Don't tell me i'll have to put up with this for wahtever reason cause I don't need 80 gigs of music on my computer half of it being duplicates.