Amazon Kindle 2:
- 6" display screen
- 2 week battery life (with wireless off)
- Ability to obtain free e-books through amazon
- New lower price
- Stores 1500 Books
- Supports various formats: AZW, TXT, Audible,, MP3, unprotected MOBI, PRC; through conversion: PDF, HTML, DOC, JPEG, GIF, PNG, BMP
Amazon DX
- 9.7" display screen
- 2 week battery life (with wireless off)
- Stores 3500 books
- Ability to obtain free e-books through amazon
- Higher Price
- Supports various formats: Kindle (AZW), PDF, TXT, Audible (formats 4, Audible Enhanced (AAX)), MP3, unprotected MOBI, PRC natively; HTML, DOC, RTF, JPEG, GIF, PNG, BMP
Barnes and Noble Nook
- 6" display screen
- 10 day battery life (with wireless off)
- Has a 2GB flash drive (around 1500 books)
- Has a fair price
- Supports various formats: PDF, EPUB, eReader, PDB, JPG, GIF, PNG, BMP, MP3
Sony PRS-700
- 6" display screen
- Battery life last for 7500 pages
- 512 MB memory card
- Higher price for the amount of features
- Supports various formats: BBeB (LRF/LRX), PDF, EPUB, TXT, RTF, JPG, BMP, GIF, PNG, MP3, AAC
Overall the Amazon Kindle 2 gives the best bang for your buck. It supports all the major formats, has a good battery life, and is the lowest price of all three e-readers.