I recently used notfred's vmware appliance on a ESX version 4 server. Worked great, but that server is getting erased and version 3.5 installed on it.
I tried using notfred's appliance on ESX 3.5 but it won't work. On ESX4 I just uploaded the contents of the folding.zip file, browsed the datastore and right clicked on the folding.vmx file and said "Add to inventory". When I try that under ESX3.5 it goes thru the process but then when I go to my machine inventory, it shows the machine but lists it as invalid.
I tried using the vmware converter and export from ESX4 to a file then re-convert and dump to ESX3.5 but the export fails on the converter. (I haven't tried the newest version of the converter YET)