Um.. Are you talking about the phone OS? If so, it doesn't come in the box. You have to download it online and it won't be available until Monday at the earliest. Did you nuke your berry?
If your talking about the Desktop Manager software, you can grab that online.
I am talking about the phone OS, i'm having issues with my contacts and i would just rather downgrade to another version, i heard .321 doesn't have that bug.
I would be very hesitant to download non-tmobile provided OS versions out of fear that someone else's firmware build might not include the setup and certificates needed to make UMA work on tmobile.