you have to install operating systems that are specific for your device. An operating system for the 8820 or 8300 will not work if you are using an 8800.
go here for the latest beta 4.5 OS (this will let you use the entire 8gb) - http://www.blackberryforums.com/gene...ilanguage.html
follow the instructions in the post.
BTW, the download page is in french. when you see the text 'Je confirme que les informations ci-dessus sont correctes et à jour' choose 'Oui'.. you can leave everything else as the default.