Where did my migrated files go?

I have just bought a Mac and have never really used one before. I migrated my files from my PC to my MacBook Pro overnight as it was going to be migrating over 50GB. It said it was successful, however I can't find anything that migrated, where is it and how can i find it? i have loked all through my finder and cannot think of where it went. My hard drive has 74gb on it so it must have transferred as this is a brand new Mac and I wouldn't have thought that it would have 74gb on it already, however I didn't look at this before doing the migration so I don't know how much was on it before migration. My PC has windows 7 on it if that helps. Can anybody help me please??