I've become a big fan of vmware, but if you undersize a virtual disk and need to expand it on Linux, brace yourself for about an hours worth of work (at minimum.)

Here's the process I eventually followed (this seems way too hard/complicated)

• BACKUP up your virtual machine!!!
• expand the virtual disk:

  vmware-vdiskmanager -x 16GB myDisk.vmdk
  

for instance this will size myDisk to 16GB (this size isn't additive it's an absolute size)

• Now you must boot your virtual machine into DOS or some OS that will recognize your disk, I went the BartPE route and added the vmware scsi driver so it would recognize the scsi disk. I couldn't find the actual scsi driver on the web fotunately I had a copy of the VMWare Converter which contains a copy of the drivers. You can follow the instructions at this site but the driver that is offered is incomplete.
• Once you've booted BartPE start diskpart and issue the following commands:
  • diskpart> list disk
  • diskpart> list volume
  • diskpart> select volumen=n
  • diskpart> extend
  • diskpart> exit
• Reboot the virtual machine, restarting Fedora (or your brand of Linux)
• Start the Linux Volume Manager (lvm)
  • Find the physical volume with lvm> pvscan
  • Resize the physical volume lvm> pvresize /dev/sda?
  • Resize the logical volume lvm>  lvresize -L 14G /dev/VolGroup01/LogVol00
  • lvm> exit
• Finally resize your filesystem with (on Fedora, other brands of linux may have a different command):

root# resize2fs /dev/mapper/VolGroup00-LogVol00

• Sheesh, that was a lot of work, the procedure for windows seems slightly easier, but I couldn't find all this information easily in one place for Fedora/Linux, good luck.