Getting Virtualization Right-
Survey the workloads that will be virtualized. Make sure that business-critical applications are certified to operate in (and are supported in) a virtualized environment. If not, find out when the vendor intends to provide such certification. If you can't determine that, it is likely not advisable to virtualize the application.
In my story about managing virtualization, I recommend some ways that IT managers can tame existing server sprawl. This sprawl can be avoided altogether at companies just beginning or planning a server virtualization if the following steps are taken.
By Cameron Sturdevant