To do a P2V conversion on Windows XP, go to VMware’s website, create a free account, then download and install the latest version of VMware vCenter Standalone Converter here.
Before you are able to go through the conversion process, you will need to download the Windows XP SP3 Sysprep Tools from here.
Open and then extract the cab file to this location:
C:\Documents and Settings\All Users\Application Data\VMware\VMware vCenter Converter Standalone\sysprep\xp
After that, you can proceed through the normal P2V conversion process through VMware Converter which is pretty self-explanatory.