Change database owner

I am about to join an internal course, and would like to prepare by installing the SQL Server Database Product Samples from CodePlex.
After the installation, the databases were owner by my login, and I would like to have the owner changed to "sa". I my case it is renamed, but that is another story.

Renaming a database in SQL Server Management Studio is done on the properties of the database in the page "Files".
When I ask for the change script by clicking the Script drop-down, I get a script that uses the stored procedure "sp_changedbowner".
The article on this procedure in Books Online (MSDN Library) notes that this feature will be removed, and that I should use ALTER AUTHORIZATION instead.
Then I rewrote the statement to use the recommendation
ALTER AUTHORIZATION ON DATABASE::[AdventureWorks] TO [sql_sa];
Please recall that I have renamed "sa".

The samples generates several databases. Six in my case.
Instead of generating a script for each database, I made a script to generate these scripts
SELECT N'ALTER AUTHORIZATION ON DATABASE::[' + [databases].[name] + N'] TO [sql_sa];' AS [DCL]
FROM [master].[sys].[databases]
WHERE [databases].[owner_sid] != (
  SELECT [server_principals].[sid]
  FROM [master].[sys].[server_principals]
  WHERE [server_principals].[name] = N'sql_sa'
);

I could have generated the scripts for the first principal, as "sa" always is the first, but maybe another day I would like to use another principal.

The generated scripts are like this
ALTER AUTHORIZATION ON DATABASE::[AdventureWorks2008R2] TO [sql_sa];
ALTER AUTHORIZATION ON DATABASE::[AdventureWorksDW2008R2] TO [sql_sa];
ALTER AUTHORIZATION ON DATABASE::[AdventureWorksLT2008R2] TO [sql_sa];
ALTER AUTHORIZATION ON DATABASE::[AdventureWorks] TO [sql_sa];
ALTER AUTHORIZATION ON DATABASE::[AdventureWorksDW] TO [sql_sa];
ALTER AUTHORIZATION ON DATABASE::[AdventureWorksLT] TO [sql_sa];