I currently have a Ubuntu server running VMware Server 2.0. I have another desktop/server running ESXi. The ESXi server has 2 Vm's of XP that I use for development. I needed to move the 2 Vm's from the ESXi server over to my Ubuntu server/ Vmware Server 2.0. Vmware has a tool they call VMware vCenter Converter. This tool allows you to move any VMware virtual machine to any version of VMware. If you have a VMware environment I'm not sure how you can survive without this tool.
http://www.vmware.com/products/converter/
