The Kindle supports Mobipocket files directly. You don't need to write a script to do that.
A cheap casioppeia allows me to read ebooks around 2001.
Typically ebook readers are larger than PMP's with larger screens. If you're going to read for a few hours, then the screen of a typical PMP becomes pretty eye-straining (due to size, contrast, and brightness).
Non-DRM Mobi books, like free e-books found online in Mobi format, or files you convert to Mobi files, are already supported on Kindle.
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