the links below run thought the upgrade process
Step by Step procedure on upgrading windows vCenter 5.5 to windows vCenter 6.5 - vSphere Arena
Upgrading or Migrating vCenter Server 5.5 on Windows to version 6.5 - Tech Communications Video Blog...
I hope this helps
Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410
