I just double checked on the Blackberry website, and 5.0 is indeed official (I need to read more thoroughly :P). If you do a search for "os", v5.0 is the 3rd result and 8900 is supported.
To restore a backup using BBSAK, click on Restore Apps. OR Go through Install CODs and just reinstall them by directing it to the Backup folder in C:\Program Files\BBSAK
Thank you so much for the BBSAK program--but I can't seem to get my old 3rd party apps back after I backed them up on there, any ideas?
To restore
To restore a backup using BBSAK, click on Restore Apps. OR Go through Install CODs and just reinstall the apps by directing them to the Backup folder in C:\Program Files\BBSAK