Version 1.42.0 of the excellent Calibre EBook management is now available at http://calibre-ebook.com/download_windows64 for 64 bit users.
“calibre is a free and open source e-book library management application developed by users of e-books for users of e-books. It has a cornucopia of features divided into the following main categories:”
It is available for Windows (both 32-bit and 64-bit), Linux and other operating systems at http://calibre-ebook.com/download.