LinuxQuestions.org - Moving Vbox partition from ext4 fs to NTFS

Hey guys.
It's me. :| Again :|
So , this time , my question is :
When i had windows vista on my pc , i used to use virtual box .. and well ... have some virtual harddisks in my NTFS partition.
I can acces and use those from my VirtualBox from ubuntu 10.04 if that matters.
Unfortunately the NTFS partition is the biggest , and i don't have enoguh space to make a Virtual machine on my /home partition (small)
So , i thought i could tell the vm to do a harddisk directly in the NTFS partition.
But it gives me some error.

Failed to create the hard disk storage /media/Data/win7ntfs.vdi.
Could not create the medium storage unit '/media/Data/win7ntfs.vdi'.
VDI: writing pre-header failed for '/media/Data/win7ntfs.vdi' (VERR_NET_OPERATION_NOT_SUPPORTED).

Result Code:
NS_ERROR_FAILURE (0x80004005)
Component:
Medium
Interface:
IMedium {1d578f43-5ef1-4415-b556-7592d3ccdc8f}

So i tried doing it in my home partition and then moving it to the NTFS,
Everything nice until installing the os in it.
It stops and just hangs there.
Help ?
how to make that virtual harddisk and put it in the NTFS partition , while still being able to use it?
why do i need it?
my school teaches me power point ... and i dont have it ...
i need a virtual machine with windows 7 .. but dont have space to put it in /home ..
i need to put the virtual disc in my NTFS partition and have problems with that
i know i can use Wine or Crossover but i'm just not in the mood of installing wine right now (it worked always well , but just that ... i don't know ... i want to feel like when i'm using it at school ... wine would give me an ugly thing... )
Thank you.