Please Pin this for all Mango user.
Here is how to connect your Messaging Hub to Facebook Chat:
On your phone, remove the Facebook account setup
On your PC (or in IE9 on the phone), go to home.live.com.
Under "Messenger social" click "Connect Facebook"
Go through the steps to connect Facebook to your Live account
On your phone, add the Facebook account under 'Settings' / 'Email and Accounts'
When it asks if you want to connect to Facebook Chat, tap 'Not now'.
Let it sync
Facebook Chat should automatically be activated as long as it has finished its initial syncing
If you want to check if it's activated:
Go to the Messaging Hub
Tap 'Settings'
Facebook Chat is the first option and should be activated. If not, you can activate it now.
done.
How large is the 7720 cab file? Zune downloads it at a somewhat slow rate as compared to 7403.