You can tackle that last disadvantage with by a solution like VMware's Virtual Desktop Infrastructure (VDI). Instead of multiple application instances running under one operating system (like Citrix on Windows Server 2003), multiple operating systems (mainly Windows XP) run as virtual machines on the same server hardware. Thin clients can connect to these virtual machines through a protocol like Remote Desktop Protocol (RDP). At that point, there is very little difference between connecting to a virtual machine and running the operating system on a traditional desktop.
This type of server-centric architecture is a many-operating-systems-to-many-devices relationship, instead of a one-operating-system-to-many-devices relationship. I see this as the natural evolution of the traditional server-centric terminal environment. However, even with the ability to run any application, VMWare's VDI still suffers from several server-centric disadvantages -- mainly the high upfront infrastructure costs thanks to its ultra reliance on backend servers for applications and data.
For large businesses that can deal with the high infrastructure costs, a VDI package might make sense. Small to medium-sized businesses (SMBs), however, may not have the budget to invest in a VDI package or they may not have IT staff with the skill set to support a server-centric architecture. For them a distributed desktop solution makes sense because they can easily handle one desktop application being unavailable, as opposed to that same application being unavailable to all of their users. New technology advancements from companies like Moka5 offer a compelling solution that combines the best aspects of a distributed desktop and a server-centric environment.
Virtualize your cake and eat it too
Part 1: An alternative ASP model
Part 2: VMware's Virtual Desktop Infrastructure (VDI)
Part 3: Moka5's LivePC
Part 4: Helping SMBs benefit from virtualization
About the author: Harley Stagner has been an IT professional for almost eight years. He has a wide range of knowledge in many areas of the IT field, including network design and administration, scripting and troubleshooting. Of particular interest to Harley is virtualization technology. He was the technical editor for Chris Wolf and Erick M. Halter's book Virtualization: From Desktop to the Enterprise and currently writes his own blog at www.harleystagner.com. Ask Harley your server virtualization questions today.