Maybe you should try buying MP3's directly from the artists via http://bandcamp.com/ or their websites. Artists make way more cash that way (oftentimes tremendously more) than they do when you buy a CD, especially if they're independent. You could probably install an auxiliary adapter to hook up an mp3 player in your car for around $100 and you'd be saving the planet too. In my old car I have a $10 tape adapter that works great with my iPhone.
For me personally, having less "stuff" is the biggest bonus of the digital age. I can't really argue with your girlfriend who "likes having physical things" except by saying that the stuff those physical things are made of is really terrible for the Earth. Buying CD's just seems socially irresponsible if you have an alternative.
Edit: Here's a little support for my carbon footprint case http://green.blogs.nytimes.com/2009/08/17/the-carbon-case-fo.... The additional thing to note is that when you buy a CD, that carbon cost is spent upfront. With an streaming mp3, the cost is distributed over time with technologies that are continuously improving in efficiency.
For me personally, having less "stuff" is the biggest bonus of the digital age. I can't really argue with your girlfriend who "likes having physical things" except by saying that the stuff those physical things are made of is really terrible for the Earth. Buying CD's just seems socially irresponsible if you have an alternative.
Edit: Here's a little support for my carbon footprint case http://green.blogs.nytimes.com/2009/08/17/the-carbon-case-fo.... The additional thing to note is that when you buy a CD, that carbon cost is spent upfront. With an streaming mp3, the cost is distributed over time with technologies that are continuously improving in efficiency.