VMware's Paul Maritz has given up his title of president to four senior executives who will serve as co-presidents of the EMC-owned company as it increasingly goes up against Microsoft in the virtualisation market. With Maritz, himself a former Windows executive, continuing to hold the CEO title, three of the top five executives at VMware are now ex-Microsoft officials.

Richard McAniff, Tod Nielsen, Mark Peek and Carl Eschenbach will be the four co-presidents, according to a filing with the US Securities and Exchange Commission.

McAniff spent 21 years at Microsoft and was the corporate vice president of Microsoft Office before joining VMware in 2009. Previously VMware's executive vice president of products and chief development officer, he was named co-president of products and chief development officer.

Nielsen spent 12 years at Microsoft and was the vice president of Microsoft's platform group. Previously VMware's COO, he was named co-president of the applications platform.

Peek's most notable former employer is Amazon.com. He was CFO and now adds the title of co-president of business operations. Nielsen and Peek have been with VMware since 2009 and 2007, respectively.

Eschenbach, who's been with VMware since 2002, held various positions at 3Com, Lucent and EMC. He was promoted from executive vice president of worldwide field operations to co-president of customer operations.

VMware essentially created the market for x86 server virtualisation, but cast off its founders Diane Greene and Mendel Rosenblum when Microsoft started making noise by adding the Hyper-V virtualisation platform to Windows Server.

VMware still dominates the market with more than 190,000 customers, including 100% of the Fortune 100 and nearly all of the Fortune 1000. But Microsoft is undercutting VMware on price and attempting to bring virtualisation to new customers by making it a feature of the operating system, instead of something that must be purchased separately.

Maritz has argued that virtualisation is making operating systems less relevant, but VMware's core business is still centered on letting customers run instances of Windows Server in virtual machines.

"From our perspective, regardless of whether customers are running on Hyper-V or VMware, first and foremost they're a Windows customer," Microsoft virtualizaton chief Mike Neil said last year. 

VMware is also facing increasing competition from Citrix and others in the growing market for desktop and application virtualisation. But in a statement released to Network World, VMware did not cite any competitors by name in explaining its decision to reorganise.

"After completing an outstanding year in 2010, and with the need to drive even greater focus across the three layers of VMware's strategy, key leaders are stepping up to make further contributions," VMware stated. "These organisational changes are in response to the tremendous opportunities before us to help our customers navigate the journey to Cloud Computing."