Upgrade SQL 2005 to 2008 checklist

Pre-upgrade checklist

• Make sure you don't have an sa accounts with blank passwords. This is a really good idea regardless.
  
• On the sql server, get your .net installation up to .NET Framework 3.5 SP1 or later. Best way to do this is to install Visual Studio 2008 SP1.
  
• For Server 2003, install Windows Installer v4.5 from the SQL 2008 media. Not needed for Server 2008.
• Make sure that all DBAs, sysadmins, and dev team leads know that they will need to install the SSMS 2008. (Still a good idea if you have SQL 2005 servers in your environment to keep SSMS 2005 and BIDS 2005 installed at your workstation, especially for replication and SSIS packages.)
  

General tips

• Easiest way I can think to do this is to install a SQL 2008 instance, detach/attach the 2005 databases to the new edition. Obviously, this creates a server with a different instance name. This may or may not be a big deal, if you can change your connections strings easily enough.
  
  In all likelihood, you'll instance want to upgrade in-place your SQL 2005 instance. This can be done through the wizard, using the option "Upgrade from SQL Server 2000 or SQL Server 2005."
  
  
• Remember that upgraded, attached or copied databases from SQL 2005 may still be in SQL 2005 compatibility mode. Be sure to do your post-implementation testing against databases in SQL 2008 compatibility mode!
  

If you have anything to add, please do so in the comments below so that others who find this blog post can benefit.

Links for more reading:
http://msdn.microsoft.com/en-us/library/ms144267.aspx
http://msdn.microsoft.com/en-us/library/bb677619.aspx
Clustered environment: http://msdn.microsoft.com/en-us/library/ms191295.aspx
http://www.sqlservercentral.com/articles/SQL+Server+2008/67066/