Computer books are usually big. They take too much space. They are more expensive than ebooks... I would consider trying a Kindle if reading pdf ebooks is comfortable. With the DX (bigger size and PDF support) coming out, I'd really like to see how it works with programming books. Using Landscape Mode seems awkward (I read that buttons are on only one side), but it might not be necessary with the DX. I don't know.
The DX only has buttons on one side - I'm not sure how I feel about that. On the smaller version that I have, buttons are on both sides, so in landscape mode I end up with buttons underneath the screen, which I find quite usable. Even in portrait mode (for when I am reading a novel), I find that I use the buttons on both sides - I just alternate whether I am holding the Kindle in my left or right hand from time to time, and use the buttons appropriately.
When I bought my Kindle, they were not offering an international version of the DX. Having bought the small version, I am very happy with it for novels, especially when traveling with it. I might consider the DX at some point, especially if it is cheap enough when they eventually offer refurbished units through Warehouse Deals.