I did this with a Ubuntu 9.04 bootable Live CD.

Boot from the CD
Choose to try Ubuntu without installing
Start a command prompt (Applications ==> Terminal)

# get root
sudo su -

# find your harddisks
root@ubuntu:~# fdisk -l

Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x9eef9eef

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        9728    78140128+   7  HPFS/NTFS

# over write the hard drive with one pass of zeros
# and tell me about it (-v)
root@ubuntu:~# shred -z -n 0 /dev/sda -v
shred: /dev/sda: pass 1/1 (000000)...
shred: /dev/sda: pass 1/1 (000000)...348MiB/75GiB 0%
shred: /dev/sda: pass 1/1 (000000)...700MiB/75GiB 0%
shred: /dev/sda: pass 1/1 (000000)...1.0GiB/75GiB 1%
shred: /dev/sda: pass 1/1 (000000)...1.3GiB/75GiB 1%
shred: /dev/sda: pass 1/1 (000000)...1.6GiB/75GiB 2%
shred: /dev/sda: pass 1/1 (000000)...2.0GiB/75GiB 2%
shred: /dev/sda: pass 1/1 (000000)...2.3GiB/75GiB 3%
shred: /dev/sda: pass 1/1 (000000)...2.6GiB/75GiB 3%
shred: /dev/sda: pass 1/1 (000000)...2.9GiB/75GiB 4%
shred: /dev/sda: pass 1/1 (000000)...3.3GiB/75GiB 4%