After two years of research on the subject, Dr McIsaac is warning users not to assume that the Total Cost of Ownership (TCO) gains made by virtualising servers apply equally when taking the same approach to the desktop.
The greatest problem facing desktop virtualisation, he said, is Microsoft's licensing strategy, which requires that every device that runs applications like Office be covered by a licence.
Microsoft is actively enforcing this policy even in cases where the applications are streamed from the data centre rather than stored on the device itself, he said.
"It's an impediment to virtualisation on the desktop," he said. "Licensing is a significant and serious problem. For medium to large organisations, it costs millions to tens of millions in compliance costs.
"The problem is most people didn't see this upfront" before rolling out desktop virtualisation projects, he added.
McIsaac said he had interviewed companies which had introduced desktop virtualisation but had failed to control or log which devices were running applications.
"The first question Microsoft asks is - do you have any control over which devices access applications?
"Without logs or controls, you can't demonstrate you are compliant."
McIsaac said Microsoft never takes companies to court over licensing breaches in their virtual environments.
"The auditors simply come in and say, let's talk about how much it costs to make the problem go away."
The final figure "is a scary number", said McIsaac.
McIsaac recommends organisations control which applications are accessible by device or user via the policies built into applications like Citrix's Smart Access.
While he doesn't see Microsoft rushing to change tack, McIsaac insists that the software giant "simply has to move to user-based licensing."
"Device based licensing is a hangover from the eighties," he said.