Depends on your needs and personal preference...
I used to use the Virtual Desktop Manager that was part of the XP Power Tools suite. At the time I working in a high volume helpdesk which required me to support hundreds of applications running on multiple platforms. I found it to be overwhelming trying to manage the upward of 20 windows/apps/webpages that I would have to have open to perform my job. Using the multiple desktops I could group related applications logically to a specific desktop. Once you were used to navigating between desktops the application worked well for its purpose. The problems that I encountered were related to confusion and system resources. Over the course of the day working between the various desktops, you would sometimes get confused and forget which application or web portal was running on which desktop, and you would sometimes open another instance of an application on a different desktop. The footprint of the Virtual Desktop Manager was small, but every application will consume system resources, and one application that hits the processor heavily will not only affect the desktop that it is running, but every desktop and application that you have running.
For the job I work now the Virtual Desktop Manager would not be a good fit. I do better using RDP tools and Virtual Machines to test out other OS platforms.
