Based on what you presented, the MBAir is perfect. I had a 7yr-old Sony. Last year is when I realized I needed a new computer. I didn't know what to get. I used that Sony for one more year and finally I put it to rest. I only use it for Word, as I haven't purchase Office for my MB Air.
Anyway, a friend told me to try the Air. I only use it to surf the web, email, youtube, hulu (when I miss a TV program I've missed), and Word.doc. It's the best fit for what I use it for. I also purchased a 4S and am very happy with these 2 new devices.
Best Buy allows you to try their computers for 2 weeks. No open box fee. I did just that, and was happy a friend turn me to Apple. Now, I have until Jan. 24th to exchange the MB Air and I'm contemplating the 15-inch MB Pro, but the only thing I don't like about it is it lacks the SSD like the MBAir. I'll be upset if the next ten 15-inch Pro's get the SSD, which rumor claims them will Q1 2012.
Edit: As far as you music, why can't you just copy the folder where all your music is stored on an external drive and import them their from iTunes on your new MBP. You can also back up, if you hadn't already, the music on your iPod, store them on your vaio, and copy them to the external and import fro there. I now these are a lot of steps, but unless you have the proper cables and apps to transfer, I think, this is the best economical solution.