Upgrade Advisor detected data or log files that are not set to autogrow. In SQL Server 2005 and later, new and enhanced features ...

Upgrade Advisor detected data or log files that are not set to autogrow. In SQL Server 2005 and later, new and enhanced features require additional disk space for user databases and the tempdb system database. To ensure resources can accommodate size increases during upgrade and subsequent production operations, we recommend setting autogrow to ON for all user data and log files and the tempdb data and log files before upgrading to SQL Server 2008.

After you have upgraded and tested your workloads, you may want to turn autogrow off or adjust the FILEGROWTH increment accordingly for user data and log files. We recommend that autogrow remain on for the tempdb system database. For more information, see "Capacity Planning for tempdb" in SQL Server Books Online.