Which Code Generator Tool have you used? suggest?

I need a code generation tool

 

The input is a SQL Server 2000 database.

 

Output: to generate Data Access Classes, Stored Procedures, Business Entity Classes & Business Logic classes related to the tables in database.

 

Which tool have you used and which tool do you suggest?

Is it worth writting a code generator tool from scratch myself or using an existing one from the web?

 

I have seen CodeSmith, I think using that I need to create Templates or using the existing templates (which gives more flexibility as well)

 

Another problem is maintainability, if I generate the output as described, then something in database is changed, how the code gen ...