While there's a growing interest in the availability of virtual appliances as well as physical devices, Citrix is keeping feet in both camps.

The company has expanded its virtual appliance range with the launch of the Branch Repeater VPX virtual appliance as well as a virtual version of its Access Gateway VPX. In addition, the company has released a set of five web application firewall physical appliances, based on the NetScaler MPX hardware platform.

The company first took steps down this route last year when it launched its NetScaler MPX as a virtual appliance, describing that move as a "game-changer". So, how does the company describe the latest move. Damian Saunders, UK sales manager for Citrix said that the company had long been intending to move the entire range to be virtual appliance but said that it had to take a measured approach. "We decided to introduce them in stages, starting with the NetScaler last year, until we can offer a complete set of virtual appliances to customers."

He said that the introduction of Xen Desktop 4 gave customers a different set of requirements to customers. "When you have a thin client - as with the traditional Citrix thin client product - then only a subset of applications is affected, but when you move to a virtualised desktop, everything changes as you're serving everything through that desktop - that move has an impact on every aspect of computing, not just a small set of applications."

As for the existence of both physical and virtual products, Saunders said that there'd always be some specialist applications that require hardware. "We're always going to have some hardware dependent applications, such as GPUs, but there's an also issue about licensing- many vendors have got some work to do there."