Switching from PC music folders to Itunes

I'm switching. Before I screw things up and make it harder than it has to be I thought I would make sure there was no easy way to do this.

I'm guessing I have to delete my current RB collection and import from Itunes so I don't double up the same songs in my collection?

Can I save a backup and use it for the same songs that are now imported from Itunes or I must start new/fresh?

What is the best course of action here?