Hey Aamir I have not tried this with ESX 4.0. But...

Hey Aamir

I have not tried this with ESX 4.0. But I don't see why you would not be able to use the VMware Converter to achieve your goal!

I'm running my ESX hosts in HA mode and taking advantage of Vmotion. I'm still currently on ESX 3.5 but our other office in London has installed 4.0 and I've helped when configure Vmotion. 3.5 and 4.0 don't seem on that different from the Infrastructure console side. Underneath is a different story but converter should still be a solid solution for you.

Let me know how it goes.