SANTA CLARA, CALIF. - January 31, 2006 -- Sun Microsystems, Inc. (NASDAQ: SUNW) today announced that exactly one year after its initial release, the Solaris 10 Operating System (OS) has surpassed 4 million registered licenses and set 57 performance and price/performance world records. The roster of companies that have registered licenses of the free and open source Solaris 10, the most advanced operating system on the planet, includes 10 of the top 11 retailers, 7 of the top 8 financial services companies, and all of the top 5 manufacturing companies and top 5 IT companies.

Customers are reporting tremendous application performance improvements from Solaris 10, the most advanced operating system on the planet. The Solaris 10 OS includes innovative features not available on other platforms, such as Dynamic Tracing (DTrace), Predictive Self Healing and Solaris Containers, enabling customers to more effectively utilize system resources, and more quickly diagnose and resolve system issues in order to maximize the hardware investment and maintain availability. The Solaris OS is the only operating system that guarantees binary compatibility on supported platforms and source code compatibility between SPARC(R) technology and x64 systems. The Solaris 10 OS also currently supports more than 500 platforms providing customers with the ability to take advantage of Solaris 10 OS on one of the broadest choices of hardware in the industry. Solaris 10 OS is available as a no cost download at http://www.sun.com.

"It's been a great year for the Solaris OS. Since we released Solaris 10, the most advanced operating system on the planet, Sun has made the OS available for free, started supporting it on more than 500 x86 systems including HP and IBM and open sourced the software," said Tom Goguen, vice president of Software Marketing for Sun Microsystems. "The results speak for themselves with 57 performance and price/performance benchmarks, 4 million registered licenses distributed, two thirds of which are on x86 systems, and a vibrant open source community that includes four separate distributions of OpenSolaris."

Solaris 10 OS is part of the Solaris Enterprise System which also contains the Sun Java Enterprise System (Java ES), Sun N1 System Manager software and Sun Studio Software Developer tools available at no cost for both development and deployment. All of this software makes the Solaris Enterprise System the the only comprehensive and open infrastructure software platform available today.

In just two years, the Java ES has surpassed 1 million subscriptions as recently announced. The Java ES is an open, standards-based software system that delivers a core set of industry-leading shared enterprise network services as a single, integrated entity on a predictable release cycle. It serves as the strategic underpinning of Sun's software strategy. For more information on the Java ES please visit: http://www.sun.com/software/javaenterprisesystem

The OpenSolaris project is an open source project that makes the source code for the Solaris 10 OS available to virtually everyone, so they can innovate and build products. Future versions of the Solaris OS will be based on technology from the OpenSolaris project, available at http://opensolaris.org.

About Sun Microsystems, Inc.

A singular vision -- "The Network Is The Computer" -- guides Sun in the development of technologies that power the world's most important markets. Sun's philosophy of sharing innovation and building communities is at the forefront of the next wave of computing: the Participation Age. Sun can be found in more than 100 countries and on the Web at http://sun.com.

Sun, Sun Microsystems, the Sun Logo, Solaris, OpenSolaris, Java, N1, and The Network Is The Computer are trademarks, registered trademarks, or service marks of Sun Microsystems, Inc. in the United States and other countries. All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International, Inc. in the United States and other countries. Products bearing SPARC trademarks are based upon an architecture developed by Sun Microsystems, Inc.