Server and Tools revenue increased in both product sales and Enterprise Services. Product revenue increased $1.3 billion or 9%, driven primarily by growth in Microsoft SQL Server, System Center, and Windows Server. Enterprise Services revenue grew $434 million or 11%, due to growth in both Premier product support and consulting services.
Server and Tools operating income increased, primarily due to revenue growth, offset in part by higher cost of revenue and sales and marketing expenses. Cost of revenue grew $589 million or 15%, reflecting a $269 million increase in headcount-related expenses and a $169 million increase in datacenter expenses. Headcount-related expenses increased due mainly to higher Enterprise Services headcount supporting revenue growth, while datacenter expenses grew primarily to support our online services offerings. Sales and marketing expenses grew $160 million or 3%, reflecting increased fees paid to third-party enterprise software advisors and corporate sales and marketing activities.