I only use the Sony software to download freebies that are occasionally offered. If you want another program to manage your collection of ebooks try Calibre
http://calibre.kovidgoyal.net/
It's a free program for managing ebooks and converting formats.
Also, depending on your reading tastes, check out the free out-of-copyright ebooks listed on this site. Check the blue bar at the top of the page for the E-books link.