Vista - Backup using up too much space

Hi,

I've recently started using the Vista Back Up application (Back up files,
not Back up computer). I have set it to back up every day however within 3
days it has gobbled up all the space on my second drive.

I am using Vista Ultimate. My C drive is a 1000 GB RAID 1 array (I do a lot
of video editing) and the E drive is also a 1000 GB RAID 1 array. I am trying
to backup data files from the C drive to the E drive.

Prior to the first back up there was plenty of space on the E drive (i.e.
there was far more free space on the E drive than there was used space on the
C drive).

I understand that Vista Backup is supposed only to update those files that
have changed, and I assume will remove previous versions of those files from
the Back up.

I have run Back up three times now. The changes and additions to the files
on my C drive have been extremely minor (just a few MBs per day). Therefore,
the changes to the E drive should have been minor too, yet I now have
virtually no space left on my E drive.

I have 385 GB free space on the C drive and just 58GB free space left on the
E drive (both are 1000GB drives). Given that I am not backing up the entire
computer the back up files on the E drive should be smaller than the used
sapce on the C drive.

The only other thing on the E drive is an XP installation (with effectively
no user data files), which I have installed as an emergency measure should
Vista become unstable and unusable again .

Any suggestions anybody?

Many thanks,