I'm neither for nor against open source. I personally do not use linux because I really don't have the time to learn how to administer it, I have enough trouble keeping current with SQL Server. I think the downside to open-source is that you are depending on a community to support the product. With Windows or SQL Server, if I have a major problem I can call support and hopefully get an answer. I know you can purchase support for MySQL and Linux, but then it's not "free" anymore. I think you need to use products that you can support in-house. If you are a Windows/SQL Server shop you probably don't want to switch to MySQL or Oracle.