Great vSphere 4 best Practice Guides:

http://vmetc.com/2009/05/24/vsphere-40-best-practices/

• Installing ESX 4.0 and vCenter 4.0 best practices
• Upgrading to ESX 4.0 and vCenter 4.0 best practices
• vCenter Server Installation Worksheet
• Upgrading an ESX 3.x virtual machine to ESX 4.0