Bah, well, from those options, you have essentially discounted the first two.

I would say that I love my macbook pro, but those things are incredibly expensive, and probably not worth it for what you do on the computer (or sounds like you do from the above lists). A macbook would probably be a great option, and refurb would make it pretty affordable.

As for your files, upload them to Amazon's cloud service. It's free for 5gb I think. If not, I know it's free for at least a year if you buy ONE mp3 album.