SAP have created a useful wiki which provides details on how to upgrade your BusinessObjects XI3 environment to BI4.
The wiki helps you to:
- Identify what to upgrade
- Taking backups prior to the upgrade
- Use of the Upgrade Management Tool
- Conversion of the Business Objects universes from .unv format to unx. format
A couple of things to be aware of:
- BI4 uses a different audit schema
- A 64bit Operating System is required for BI4
Certainly worth a read prior to undertaking the upgrade.
The link to the wiki is open for all and can be found here: