a note on converting PDF. I really struggled with this myself in Calibre (a fantastic piece of software) however trawling the web I came upon this solution.
First convert the PDF file using mobipocket creater (free software) and then convert the output file – prc or html – to epub in Calibre. You will get a much better quality file, though you may need to play with the paragraph settings in calibre so you don’t get a blank after each line.
Found this really useful for work documents that tend to be only published in PDF and which I don’t want to have to open up my laptop to reference.