As the adage goes, you get what you pay for! Many of the free software versions don't have: integration with storage; management software integration; 24x7x365 support; or the growing number of main, third party and application support.
For an environment that does not require advanced features, complicated storage attachment, or monitoring and management, freeware may be suitable. But for production (and even non-production) environments, you will want to have the reliability and dependability that comes with support, integration, and high availability.
This was first published in March 2007