A solid working knowledge of productivity software and other IT tools has become a basic foundation for success in virtually any career. Beyond that, however, I don't think you can overemphasise the importance of having a good background in maths and science.
Me, I just don't care about proprietary software. It's not "evil" or "immoral," it just doesn't matter. I think that Open Source can do better, and I'm willing to put my money where my mouth is by working on Open Source, but it's not a crusade – it's just a superior way of working together and generating code.
This existing base of FLOSS software represents a lower bound of about 131,000 real person-years of effort that has been devoted exclusively by programmers. As this is mostly by individuals not directly paid for development, it represents a significant gap in national accounts of productivity. Annualised and adjusted for growth this represents at least 800 million euros in voluntary contribution from programmers alone each year, of which nearly half are based in Europe.