"What I want to argue is that open source isn't all its cracked up to be, and that as a consumer, there's nothing inherently wrong or stupid (as wmarone seems to believe) with buying the superior product."

Jeez what do you think OSS is cracked up to be? For your needs proprietary software seems the most reasonable choice. I write this because, 1. you are fine with your machine being "locked down" as long as your media, games, and what not are well integrated into your computing experience and 2. you appear to want to minimize the amount of work you need to do to actualize this goal. On the other hand I like to make/build/fix things: book scanners, genealogy lists, repairing old homes, etc., and I use my computers to help me pursue these interests. For me OSS not only is in line with my desire for a symbiosis of work and creativity it is a life saver in terms of the amount of time I can save by customizing code to do what I want and working with the developer(s) to achieve my goals.

TBH I'm rather surprised to find someone with your needs on this forum, but life is full of surprises. Do what is best for you and I think everything will work out.