The problem is that the Windows brand is reliable in the same way that Walmart is reliable. Everyone has a Windows machine, but few people "love" it.
This is the thing I never really got about Microsoft rebranding all of their core technologies to be "Microsoft" or "Windows" branded. They fell into the (disappointingly common) trap of saying "We have two brands. One is great - one is ok, but we all identify more with the OK brand. Let's fold the great brand into the OK one and people then we will get the kudos that was previously going to the great brand".
Xbox was more of a luxury brand when it didn't have Microsoft's logo splattered all over it. Lionhead studios is a better brand than Microsoft games, and "Windows Live Hotmail" was a vastly inferior brand to "hotmail".
I think perhaps some executives at Microsoft should go on a little two day "brand awareness" course to understand what consumers actually feel about brands, and how they can be exploited.
If they wanted Microsoft Surface running Windows RT to have sold better, they should have just differentiated the brand by calling it "Surface", and dropped the whole "Microsoft" and "Windows" branding from it.
Much as I hate to say it - Apple has already learnt this lesson. "Apple" is not a cool label. The "i" prefix is. That's why they don't call their product "Apple Phone RT with User Accessibility Compatibility Extensions XP 2004 Customer-Orientated Edition"