Using VirtualBox you could face the problem of an hard disk too small. It’s not possible to change the size of the virtual hard disk (.vdi) directly so we have to find an other solution.
I solved this problem by creating a new virtual hard disk and clone the old hard disk in the new one.
What you need:
- Gparted iso image
- SuperGrubDisk iso image
This is the simple guide:
- Create a new virtual hard disk (with the new size) using virtual box.
- Associate this hard disk to your virtual PC (so you will have two hard disks)
- Mount GParted iso file in virtual PC’s DVD drive and set the DVD as primary boot
- Start your virtual PC and boot into GParted
- Select the old disk partition and copy it, then select the new partition and paste
- Apply the modifies in GParted and shutdown the virtual PC when finished
- Remove the old hard disk from your virtual PC and set the new one as primary device
- Unmount the GParted iso file and mount the SuperGrubDisk one
- Start the virtual PC and select the right selection in the menu; I used MBR & Win because the ghost machine is a Windows XP
- Shutdown, unmount the SuperGrubDisk iso file and enjoy
That’s it.
Bye,
Ivan

Excellent
thk you very MUCH for your recipe
Thanks for this useful post !
Thanks! Works great with Ubuntu 11.10.
Or do this (MUCH easier): http://ttcshelbyville.wordpress.com/2011/10/23/increase-hard-drive-size-in-virtualbox/
Thanks for sharing Michael, this blog was written in 2009 and that version didn’t allow that you linked