How can I easily add storage to a VirtualBox machine with XP installed?

I found this nugget at the link following. It worked perfect for me and only took 5 seconds.

As of VirtualBox 4 they added support for expansion.

VBoxManage modifyhd filename.vdi --resize 46080

That will resize a virtual disk image to 45GB.

https://superuser.com/questions/172651/increasing-disk-space-on-virtualbox

Note: This applies to pre-4 VirtualBox. In VB4, HDD expansion has been introduced.

According to the VirtualBox documentation:

When creating an image, its size needs to be specified, which determines this fixed geometry. It is therefore not possible to change the size of the virtual hard disk later.

So, the easiest way to add additional space to an existing VM is to attach a second hard disk. Go to the VM Settings > Hard Disks > Add New. Then, click the "Select Hard Drive" button and click on "New". Follow the wizard to create a new virtual hard disk. It will then show up as D: or E: in your guest OS.

For Windows users there's an additional user friendly option: CloneVDI Tool by mpack. It's a GUI front-end to VBoxManage that makes things a little easier to work with.

http://forums.virtualbox.org/viewtopic.php?f=6&t=22422

As Alexander M. mentioned, you'll still have to use GParted, Partition Magic or a similar partition editor to grow your partition to the newly allocated physical drive. To do this just download the GParted iso, mount it as a bootable drive in the VirtualBox and boot from it.

http://gparted.sourceforge.net/download.php