Yea, ummm,
Calibre 
I only say it like that because it has been mentioned in the last many posts about people having problems with Sony's software.
Learn it, live it, Love It!!!
Happy Reading....
Also, if the book is in a format 300 can view natively and it is not DRM's, you can just drag and drop it into the drive that gets created on your PC when you plug in the usb cord.
X:\database\media\books (X will be the new drive letter) This is where the books go on my 300