There are some very good comparison between the two here:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR2ENG7W9CDIXYH%3Fie%3DUTF8%26ref%255F%3Dcm%255Fcr%255Frdp%255Fperm&tag=searchresult-20&linkCode=ur2&camp=1789&creative=390957

http://ebookreader.ebestreview.com/amazon-kindle-dx-vs-kindle-2

I’ll say if you can afford the money then get the Kindle DX. It is still handy as you can see in the first review. And even if you don’t read complicated PDF files too often, it is always good to get a device with better capability, as you never know whether you need the enhanced functions in the future.

And I won’t choose ebook readers other than the Kindle too. Amazon is giving huge content for their Kindle device, no other company (including Sony) can compare. It offers ebooks at a price cheaper than actual books, and this cannot be done by other readers too… Remember, the content you can get for your ebook reader is the most important, as it is the content which make ebook readers useful to us.

Hope this helps you decide.

The first Kindle had poorer resolution. The Kindle 2 has the same as the DX, 16 gray scale. FYI: Sony has two new editions and a third one available for pre-order that uses AT&T wireless. I have a Sony and a Kindle 2. I prefer the Sony device because it’s not so large with all the wasted space of the keyboard like on the Kindle. I also prefer the Sony software, but their ebook prices are sometimes much higher than Amazon’s.

Asus is planning a reader with two full-color screens connected in the center like a real book and it’s wi-fi enabled so you can read a book on one side and surf on the other. I’ve read that it’s supposed to be at a great price too and will hit the market by the end of the year.

I’ve the Kindle 2 and I like it very much. I think if you need to read PDF with complicated tables or charts then you should get the Kindle DX. Otherwise it is good enough to have the Kindle 2. I remember I read this review when I decided to get the Kindle 2:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR2DUM7S4XW06QN%3Fie%3DUTF8%26ASIN%3DB00154JDAI%26nodeID%3D%26ref%255F%3Dcm%255Fcr%255Fpr%255Fcmt&tag=moreinfo-po-20&linkCode=ur2&camp=1789&creative=390957

And I recommend this review, it should help you decide whether to choose the Kindle 2 or the Kindle DX:

http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Freview%2FR23V08M2LNB81I%3Fie%3DUTF8%26ref%255F%3Dcm%255Fcr%255Frdp%255Fperm&tag=moreinfo-po-20&linkCode=ur2&camp=1789&creative=390957

Don’t choose the Sony Reader. I’ve a number of friends having the Sony Reader, and they often complain that it is difficult to find books, and books are more expensive compared to books on the Kindle…

Hope it helps