http://blogs.technet.com/b/tonyso/archive/2008/08/12/hyper-v-server-sizing-how-much-memory-for-the-host.aspxThe Performance Tuning Guidelines for Windows Server 2008 has been updated to include perf guidelines for virtualization servers. To calculate the host RAM = (VMRamRequirementMB x #ofVMs) + (#of VMs x 32MBVMOverhead ) + (512MBHost), The guide says: .en-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)http://blogs.technet.com/b/tonyso/archive/2008/08/12/hyper-v-server-sizing-how-much-memory-for-the-host.aspx#3106545Fri, 15 Aug 2008 16:30:25 GMTd5e57398-b9ef-4490-9955-07cbb4e4a80d:3106545Lior Arviv's Blog<p>Here are some recommended links talking about performance tuning and right sizing when planning a deployment</p> <img src="http://blogs.technet.com/aggbug.aspx?PostID=3106545" width="1" height="1">