What is the easiest way to upgrade from ESX 3.5 to ESX 4.1 and Also from VC 2.5 to VC 4.1 ?
Welcome to the Community - follow the VMware Upgrade Guide - http://www.vmware.com/pdf/vsphere4/r41/vsp_41_upgrade_guide.pdf
Curious why aren't you moving to vSphere 5?
Welcome to the Community - follow the VMware Upgrade Guide - http://www.vmware.com/pdf/vsphere4/r41/vsp_41_upgrade_guide.pdf
Curious why aren't you moving to vSphere 5?
You have to get over the hurdle of going to a 64bit system running vCenter. I did a slightly unconventional way of transitioning 4.0 to 5.0. But it went as smooth as silk, and I have no regrets.