Windows Division revenue reflected relative performance in PC market segments. We estimate that sales of PCs to businesses grew approximately 11% this year and sales of PCs to consumers declined approximately 1%. The decline in consumer PC sales included an approximately 32% decline in the sales of netbooks. Taken together, the total PC market increased an estimated 2% to 4%. Revenue was negatively impacted by the effect of higher growth in emerging markets, where average selling prices are lower, relative to developed markets, and by lower recognition of previously deferred Windows XP revenue. Considering the impact of Windows 7 launch in the prior year, including $273 million of revenue recognized related to the Windows 7 Deferral, we estimate that Windows Division revenue was in line with the PC market.
Windows Division operating income decreased as a result of decreased revenue and higher sales and marketing expenses. Sales and marketing expenses increased $224 million or 8% reflecting increased advertising of Windows and Windows Live.