The advantages of using virtual workstations on a computer outweigh many of the disadvantages. I have been running Lightroom 2.1 now in a virtual machine for over a month with no adverse effect. The virtual machine, however, uses both processors and 2Gb of the 4Gb of machine memory. There is one trick to help keep the speed of the interface up.
The viewing mode of the virtual machine is important. We easily get used to windows around our desktop and the ability to switch between them easily. When using a virtual machine, a window is a resource hog. The machine should be running and the windows should be within the virtual machine.
The best response in the virtual machine is had when the view is set to Full Screen. This is found on the View, Full Screen menu. Using Full Screen there is no part of the host machine visible. This means the computer will not have to spend as much time keeping up with the host and can focus on your virtual machine.
The next tip I will publish is regarding the screen size in a virtual machine. When using VMWare on a laptop, sometimes the docking monitor is square and the laptop screen is wide. I have an easy method to switch between the two resolutions in Windows.