"Starting with version 2.5, the eBook Library software is now compatible with 64-bit versions of Windows Vista for the PRS-505 and PRS-700 series of the Digital Readers. If your computer uses a Vista 64-bit operating system, please download and install the newest version from our website at:
http://ebookstore.sony.com/download
Our new eBook Library software is not compatible with 64-bit versions of Windows XP and does not add support for Vista 64-bit on the original PRS-500 series. However, the PRS-500 Reader does not require you to install the eBook Library software to load or view supported files. The Reader supports both Sony's Memory Stick and SD Memory Card media for direct file transfer. Simply insert media containing files you wish to view and any compatible content will automatically be displayed in your book list regardless of your installed operating system."