Jewel,
the upgrade addresses a few issues within the camera, including upgrading the AF ( autofocus ) multizone sensors etc to improve performance , there are also a few other upgrades that will improve the camera, albeit small ones,
the process is easy to do and just follow the link in the first post,
however, take heed of the warnings, the upgrade may if interupted render the camera inoperable and will need to go back to a dealer to be fixed,
but i found it ok to install myself
hope this helps
MP