Hi,
It would be worth giving PaperCrop:
http://code.google.com/p/papercrop/ a go. It crops your PDFs into smaller chunks, divides up columns etc.
It has a lot of presets for different types of documents.
If any of the technical books you bought have are from SitePoint you can redownload them as
mobi format which is used on the Kindle. Some other technical publishers may offer their books in
epub format but you should be able to convert these using Calibre into mobi format.