The sVmotion GUI is part of the vSphere 4.0 release of vCenter, you will have an option to specify the destination disk format whether you want that to be thin or not. Once you upgrade your ESX(i) / vCenter to 4.0 then you'll have this option for your VM(s)
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William Lam
VMware vExpert 2009
VMware ESX/ESXi scripts and resources at:
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