>OK I dowloaded SQL Server 2008 r2 Developer
>
>I started the install
>and I get an error:
>[Error Message]
>The credentials you provided for the SQL Server Agent service are invalid. To continue, provide a valid account and password for the SQL Server Agent service.
>
>[Details]
>Microsoft.SqlServer.Configuration.Agent.InputValidationException: The credentials you provided for the SQL Server Agent service are invalid. To continue, provide a valid account and password for the SQL Server Agent service.
>================================================================================

It should give you the option to use existing Service accounts (a dropdown list). Pick one of them - they do not need a password.

>
>what shall I use for credentiosn
>it reports the same errors also for
>server database engin and integration services
>
>thanks
>
>Peter
>
>>
>>Both SQL Server 2012 or SQL Server 2008 R2 SP1 Developer's editions will allow you to develop applications. However, if you want to write applications for the clients and you can not predict which SQL Server versions they will have, then SQL Server 2008 R2 SP1 may be a better choice. You also probably will not use some of SQL Server enhancements if you want to keep support of SQL 2005 (say, don't use DATE/TIME types and MERGE command).