When creating a conversion to virtual machine job, the location of the ISO image file must be entered. The file is needed to enable the installation of the drivers for the appropriate hyper visor during the conversion job.
The ISO tools files can be found in the following locations:
For Hyper-V: ...\Windows\system32\vmguest.iso
For VMware: http://www.vmware.com/download/packages.html
Note: The same file can be used for both ESX 4.x and 5.0