When running psconfig (Products Configuration Wizard), and providing database server name, the following error appears: SQL Server at [server name] has an unsupported version".

See the minimum versions of SQL Server required to the SharePoint 2010 installation on same farm:

•SQL Server 2008 Express Edition Service Pack 1, version number 10.0.2531;
•SQL Server 2005 Service Pack 3 cumulative update package 3, version number 9.00.4220.00;
•SQL Server 2008 Service Pack 1 cumulative update package 2, version number 10.00.2714.00.

It´s very important to remember that SQL Server SP1 is necessary on SQL Express. If SQL version is paid (Professional or higher), it´s needed the SP1 Cumulative Update 2 too.