Organisations seeking the most cost-effective way of provisioning user desktops are best served by a Citrix-based architecture rather than virtual desktop infrastructure (VDI), according to consultancy and services provider Centralis.

But a mix of delivery mechanisms offers the most flexibility, particularly application virtualisation, says the firm.

Desktop virtualisation has been a hot topic of late, as it offers the opportunity to pull user accounts back into the datacentre, giving greater central control while retaining many of the advantages of each user having their own PC. Vendors such as VMware and Citrix have introduced entire suites of products designed to let firms move user environments into virtual machines hosted on servers.

"Hype around virtualisation is enormous. There's been substantial interest around VDI for business continuity and when people need to access applications from anywhere," said Centralis managing director Ewen Anderson.

The company is a partner of VMware, Citrix, and Microsoft, and specialises in helping customers with application delivery and desktop management. As such, the firm has a handle on what strategies work in practice, and on what technologies many large organisations are currently deploying.

"The most cost-effective method is still Citrix XenApp [formerly Citrix Presentation Server], especially as the latest quad-core processors allow you to support many users on a single server," said Anderson.

Because many resources are shared between user accounts, higher densities are possible than if each user has their own XenDesktop virtual machine, he said.

But many firms are still buying desktop PCs, not just because these offer the most operational flexibility, but also because the cost of these systems has now come down to just a few hundred pounds.

Anderson singled out application virtualisation as the key to delivering flexibility to businesses. This technology packages up applications into a self-contained environment so they can be easily deployed, in some cases simply by copying a single file to a user's desktop.

"Application virtualisation enables you to take an application and deliver it to workers, whether they are using terminal services, a laptop, or a virtual machine – the same application then works across all these," he said.

In particular, the technology complements virtual desktop infrastructure, as it allows companies to maintain just a library of basic virtual machine images that can be provisioned with applications as necessary, depending on which user logs on.

Anderson said that centralised desktops are typically being deployed initially to meet the needs of a specific department or group, such as for business continuity purposes or to enable workers to have access to applications from anywhere.

"It's often to do with mobility [at first], then it gains a life of its own as users want the flexibility this approach gives them," he said.

However, a remote desktop is not yet suitable for all worker roles. Demanding applications involving graphics often still need to be run on a local workstation, but thin-client terminals are improving all the time, according to Anderson.

"There will soon be a new generation of thin-client devices with better components, more memory and more PC-like capabilities," he said.

“Users often like the almost instant-on capability offered by thin clients when compared to Windows PCs.”