http://www.t-mobileapps.com/download...tail.cfm?ID=45
this is firmware for the handset. if you want the desktop manager software, you can download from the link above posted by bfrye.
or there are newer versions available directly from
www.blackberry.com (3.6.3.11 is the latest - 3.6 SP3a).
i believe you are mixing up desktop software and handheld software.