Back on-topic, and from a practical standpoint, I have yet to find
any book that I want to read that is either not available on Amazon for my Kindle, or is not available in a Kindle-accessible format from other sources. I have apps installed on my Windows 7 64-bit operating system Intel quad core powered overclocked computer (i.e. PC

) to handle any purchases I might desire from B&N, and Borders that are DRM-crippled, and I use
Calibre when necessary for conversions from other formats. The only potential issue is with library eBook loans, and so far that is a non-issue for me.