Gartner believes that virtualization reduced the x86 server market by 4% in 2006. As hypervisor prices drop sharply and management costs decrease because of increased competition, virtualization will have a significantly larger impact. Gartner predicts that more than 4 mln virtual machines will be installed on x86 servers by 2009. The use of PC virtualization is also set to increase rapidly. The number of virtualized PCs is expected to grow from less than 5 mln in 2007 to 660 mln by 2011.