This is a great little tool if you wanna extend the OS drive of a VM. Go into vShere and give your VM's OS HD an extra few gigs.
BTW - you can do this HOT. So, if you're going from a 20GB drive to a 40GB drive, then you will run this little exe from the VM itself. Opens a CMD window.
Volume to Extend, type C:
Size to expand the volume, type 20480
now go check your HD size in Windows Explorer :)
Download it here: Dell ExtPart