Secure Delete

If you want to erase information on Windows I have a tool to recommend
It is Secure Delete from Sysinternals
Sysinternals Tool Suite is now part of Microsoft
Secure Delete is a free data erase program coded by Windows Guru Mark Russinovich

The advantages of Secure Delete is

1. No installation required
2. Part of a Windows OS troubleshooting suite
3. It is free
4. It is very easy to use however there is no fanciful GUI everything is done via command line
5. It is a Microsoft Product so no compatibility issues
   

First go http://technet.microsoft.com/en-us/sysinternals/default.aspx
I have linked Secure Delete software directly here
Or you can download the entire Suite (Inclusive of other tools) here

Download & extract to a folder like (eg.C:\Program Files\SysinternalsSuite)

To add Secure Delete to Command Line do as follows:


Note: You need to ensure every entry is delimited by a ";"
As shown below

;C:\Program Files\SysinternalsSuite;

To use Secure Delete to delete files

1. Select Command Prompt or Type "cmd" in Run
   
2. Right Click "Run as Administrator"

Note:
You specify -p X where X is the number of times to overwrite the file so it can't be recovered

To clean the harddrive free space do as follows:


Again you can specify how many time you want to clean your C:\ by adding "-p X" to the command

Using SDelete

SDelete is a command line utility that takes a number of options. In any given use, it allows you to delete one or more files and/or directories, or to cleanse the free space on a logical disk. SDelete accepts wild card characters as part of the directory or file specifier.

Usage: sdelete [-p passes] [-s] [-q]
sdelete [-p passes] [-z|-c] [drive letter]

-c	Zero free space (good for virtual disk optimization).
-p passes	Specifies number of overwrite passes.
-s	Recurse subdirectories.
-q	Don't print errors (quiet).
-z	Cleanse free space.

Enjoy =)