get hirens boot cd & use norton ghost in it..
start the virtual machine with boot cd image & select norton ghost from backup tools
the select local ->partition to image or disk to image (in your case) & save it to your local drive
create a new VM with larger HDD size & restore the image to new one with GHOST by booting up the cd ->backup tools->norton ghost
select local-> disk from image or partition from image (depends on how you backed up) and restore the image to the new VM..http://www.hirensbootcd.net/