I'm currently looking after Windows Server 2008 which has a C drive that has 20GB of memory (but only 1.5GB is free). I'm pretty sure it's going to run out of space pretty soon. I think it's due to several system updates (which I can't control). Would it be possible to reduce the space allocated to the disks, which would make the C drive bigger? Here's some more information. Thanks for the help.

E:>diskpart

Microsoft DiskPart version 5.2.3790.3959
Copyright (C) 1999-2001 Microsoft Corporation.
On computer: STCFTHOFTS

DISKPART> select disk 0

Disk 0 is now the selected disk.

DISKPART> detail disk

NVIDIA  MIRROR   232.88G
Disk ID: FFFFFFFF
Type   : SCSI
Bus    : 0
Target : 1
LUN ID : 0

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     C                NTFS   Partition     20 GB  Healthy    System
  Volume 1     E   VOL1         NTFS   Partition    100 GB  Healthy
  Volume 2     F   New Volume   NTFS   Partition     94 MB  Healthy
  Volume 3     J   New Volume   NTFS   Partition    113 GB  Healthy