Migration Software Trouble

Hi!

I've just transfered all the data in my old Macbook Pro to my new one using the migration software tool (if you want to know why I had 2 macbooks in one year I'll gladly explain later).

The problem is that the guy from the store did this twice because of a problem on the first try. What happened was that the hard drive of the new computer was almost completely full, which is impossible considering that i only had 60 Gb in the old computer and the new one has a 160 Gb hardrive. I obviously found and deleted repeated info but I still have about 40 Gb of filled disk space for which I have no justification.

I have no idea what's using up all the space . Can anyone please give some insight?

Thank you very much

João