[Hampshire] Creating a minimal sized disk image (VirtualBox)

Hi all,

I'm trying out virtual box in an attempt to avoid having to reboot my dual
boot machine again :).

I've removed all the junk from my Windows partition and it now only uses
up 13 gigs.

What I would like to do is to create a VirtualBox image that I can then
use inside virtual box. I don't want to risk using the partitions directly
at this point in case something goes wrong!

I can use VBoxManage converfromraw to convert a "dd" image into a virtual
box image to use, however the problem is my partition size is 110gigs,
with only 13 gigs in use and of course dd would just create me a 110gig
image.

I thought about creating a new partition on the disk and copying the data
across, but that seems very inefficient way of doing it, and I don't have
any free space which means scary partition resizing on my live system! I
cannot afford to have any downtime at the moment or my project manager
will shoot me! tbh he'd probably shoot me if he knew I was even looking at
this, but it gives me something to do while I'm waiting for compiles ;)

Any suggestions of tools on Linux I can use to create a minimal image of
this data on my windows parition?