VMware, which makes a hypervisor that is present in most of the world's largest IT systems and which will reveal its quarterly numbers April 20, is certainly a leading figure in the virtualization software business.

However, other market indicators are coming to the fore, and most of them are pointing to one very clear trend: Virtual desktops are picking up momentum in replacing conventional client/server desktops.

Jefferies & Co. came out with some virtualization research April 19, reporting that 44 percent of enterprise reseller respondents to its latest survey-the highest figure yet in this category-said they believe there is high interest in virtualizing hundreds or thousands of corporate desktops across an IT system.

"VMware is heavily marketing their [virtual desktop installation] products, and their efforts seem to be resulting in increased awareness of both their solution and Citrix's," Jefferies said in its executive summary. "Some VARs see VDI as the next logical step after application virtualization."

VMware and Citrix Systems have been Nos. 1 and 2 in the VDI market for the past several years, according to IT research companies Gartner, IDC, The 451 Group and Forrester.

The main cause of this trend? Frankly, many companies are rethinking the conventional client/server desktop setup and beginning to see it as a thing of the past, as yearly licensing becomes a drag on expenses and as software upgrades and weekly security patching continue to be thorns in the sides of IT administrators.

The main objections to VDI in the past have been performance issues, such as latency, and the expensive overall entry to the technology.

Virtualization of corporate desktops is a major paradigm shift from conventional single-purpose desktop computers and servers. Like virtualized servers and storage arrays, VDI uses a centralized pool of computing power-either inside a data center or from cloud computing services-that encompasses any number of desktop workstations, enabling performance gains and a lessening of the electrical energy used to run them.

New companies such as Kaviza, NComputing and Parallels offer lower-cost VDI alternatives for small and midsize businesses, while market leaders Hewlett-Packard, VMware and Citrix aim for larger enterprises.

Kaviza provides built-in high availability, does not require shared storage and is a turnkey deployment. NComputing offers a performance-based, hardwired VDI that it says is ideal for classrooms of up to 30 users. Parallels' offering features enterprise-class manageability tools while maintaining a familiar-looking user interface.

"Windows 7 upgrades are causing IT departments to reassess their entire desktop infrastructure," Jefferies said. "Ironically, some customers are looking to use VDI as a way to increase life of their existing hardware. IT buyers in health care and education verticals are the most frequently cited users of VDI, mostly due to their interest in sharing hardware among diverse end users as way to save money."

Jefferies said resellers expect virtualization software sales in 2010 to increase about 13 percent over 2009. The researcher said the high expectations for virtualization are due largely to the improving world economy and resultant loosening of IT budgets.