The overall concept of Total Cost of Ownership for server clusters has been an important issue within the IT community for many years. Since TechWise Research last studied clusters in 2004, HP, IBM and Sun have all introduced new server hardware as well as updated operating system and cluster software. TechWise Research conducted this new study Quantifying the Total Cost of Ownership for Entry-Level and Mid-Range Server Clusters to provide more current information on this important topic. This study focuses on the entry-level and mid-range server clusters: HP OpenVMS Integrity, IBM AIX System p5, and Sun Solaris Sun-Fire clusters. This study shows that the differences in TCO between these three cluster brands can be quite significant and can easily amount to hundreds of thousands of dollars over three years.