In this document, we'll look at how we can upgrade our VMware vCenter environment 4.0 to VMware vCenter 4.1, eye! we will take into account that in the source installation we have the vCenter in a 32 bits and (As we know) vCenter 4.1 can only be installed in systems of 64 Bit, therefore we are going to have to migrate all the configuration of a server (x86) to another (x64). If the source server is already 64 bit there would be so much complication. Once we have updated vCenter and its components to the 4.1 we will now be able to update the ESX hosts(i) a 4.1.