Well you actually have more then two options as suggested by KumarLande. What IMO is the the most obvious option is simply to expand the current Windows volume to make use of some or all of the existing unallocated space already present in the virtual hard disk.
Other option similar in outcome of VMware vCenter Converter Standalone is to use disk imaging software like Symantec Norton Ghost or Acronis True Image, etc. to more easily and efficiently image the Windows volume to and new right-sized virtual hard disk and swap out the disks.