How much does your software really cost you? Here are a few links to case studies and articles about open source in business, and the economics of open source...

• Your Open Source Plan
• Rockin' on without Microsoft
• The Risks of Closed Source Computing
• Why Open Source Software / Free Software (OSS/FS, FLOSS, or FOSS)? Look at the Numbers!
• SO10 Explore Open Source Alternatives
• The war is over and Linux won
• Free/Libre and Open Source Software: Survey and Study
• The Economic Motivation of Open Source Software: Stakeholder Perspectives
• German Government Drinks to the Greatness of Linux 
• UK Government Backs Open Source