what you should do
1)create a BACK UP with the application on the phone
2) DISABLE MSN SKYPE ETC instant messaging accounts
3)DISABLE EXTRAS AND EXTRAS-DEVEL RESPOSITIES FROM THE APPLICATION MANAGER
4)DELETE AS MANY APPLICATIONS AND THEMES AS POSSIBLE
5)RESTART YOUR PHONE
6)PERFORM THE UPDATE
7) RESTORE YOUR APPS AND THEMES FROM THE BACK UP



if you dont understand something let me know