There's a known problem with the reader software on the Kindle Fire; it seems that not all Kindle- or Mobipocket-format books that were readable on the earlier products are readable by the Fire.
FWIW, I believe that the Nook Color is down to $199 from B&N (the Nook Tablet is $249, and reportedly doesn't take the N2A card), or less if you get one used on eBay, and the N2A cards run from $40 to $100, IIRC. You only really need the larger cards if you intend to download a lot of video and audio; even the smallest of the cards gives you enough space for a good selection of anti-boredom apps plus a decent library.
I keep my NookColor's brightness set pretty low, and it's still damn good even in ordinary office lighting. For using it outdoors, though, I need to set it higher. Battery life is pretty good.
FWIW, I believe that the Nook Color is down to $199 from B&N (the Nook Tablet is $249, and reportedly doesn't take the N2A card), or less if you get one used on eBay, and the N2A cards run from $40 to $100, IIRC. You only really need the larger cards if you intend to download a lot of video and audio; even the smallest of the cards gives you enough space for a good selection of anti-boredom apps plus a decent library.
I keep my NookColor's brightness set pretty low, and it's still damn good even in ordinary office lighting. For using it outdoors, though, I need to set it higher. Battery life is pretty good.