My macbook has been acting strange lately.

1. My photo library has disappeared,

2. the Itunes library disappeared even without an upgrade of Itunes. I did manage to get the itunes library back as it had happened before and I knew how to do it, the pixs are still gone.

Could it be because the disk of 60 gb is getting a bit full. I have 19 gb left. I have an external harddisk, still learning how to use it, but I'd actually like to replace the internal harddisk with something a lot bigger. Is that doable without losing everything on the disk.

Memory is 1 GB, I suppose I could start with doubling that.