An astonishing number of second-hand PCs come with an unexpected bonus of valuable personal or business information.
Short of physically destroying the hard-disk or writing new data over the entire surface, it is quite difficult to put this information ‘beyond use’ though only high-security users would go to such extremes.
For most Windows users, a few basic steps should be sufficient:
If you have followed the discipline of creating your documents in ‘My Documents’ (now called simply 'Documents' in Windows Vista) and subsidiary folders, you can manually delete the relevant documents and subsidiary folders—for less-disciplined types, it's worth using the Windows Search facility to see if there are any common user file types (*.doc, *.xls, etc) elsewhere in the file structure.
Be aware, however, that deleting files only sends them to the ‘Recycle Bin’ from where they can be recovered—you can empty the bin with the Windows ’disk cleanup’ routine which can also remove various other files including the stored pages from recent web site visits.
Outlook and Outlook Express have a similar but independent ‘recycle’ system so it is necessary to ‘empty deleted items’ for permanent removal of emails and contacts.
You should also remove email account details using Tools/Accounts (exact wording varies between Outlook versions).
emails, contact details and accounts can be removed manually though ‘advanced’ Windows users may find it easier to search for and delete the underlying data files—extensions *.pst *.dbx *.wab *.wab~
Be sure to log-out of any automatically-connecting on-line services such as MSN Messenger and Skype—disable or delete any automatically-connecting internet connections.
Many applications (accounts software, for example) maintain data in their own folder system which is usually retained even if the software is uninstalled—you need to find and delete the relevant data files if the software doesn’t provide for direct deletion.
Delete ’cookies’ (small files which pass data to web sites) using the Tools/Options (or similar) facility of your web browser.
Be sure to thoroughly test all changes to ensure that no valuable information is accessible.
An alternative approach is the ‘clean’ re-installation of Windows which deletes all files on the operating system drive (usually C:).
This is a lot simpler and more-secure than cleaning-out user information from multiple locations but it does mean that all required applications software will need to be re-installed.
A number of manufacturers (Dell, for example) provide a separate disk partition which enables restoration of the PC to 'factory settings' which will basically set up the PC 'as delivered'—use this, if possible, to ensure that there are suitable software drivers for all installed hardware.
There are various ways of getting to the 'disk cleanup' routine and the easiest, in both Windows-XP and Vista, is probably via the 'My Computer' link.
- Start / My Computer
- Right-click on the drive you wish to clean-up (usually C:) and select 'Properties'
- Click the 'Disk Cleanup' button and follow the instructions
- Repeat for any other disk partitions (each partition has a separate drive letter even though it may be on the same physical disk)
For some time, I have used the 'Quickclean' facility of McAfee Internet Security as a more-powerful alternative to the Windows disk cleanup routine—This can be set to run as a regular task and, if required, will also 'shred' the data by writing over it several times to render it permanently inaccessible.
In addition to emptying the recycle bin, McAfee Quickclean can be set to empty Outlook deleted (& sent) items, browser history, cookies, temporary internet and various other files.
Not Clean Enough?
As mentioned in my article on Raising the Dead, it is always possible, using appropriate software, to recover data which has been deleted but not physically overwritten.
A quick Google search on "Shred Files" reveals plenty of low-cost software products which can accomplish the task of permanently deleting such data by overwriting it.
For example, Active@ Killdisk can erase data from an entire hard disk, individual disk partitions or just the space marked as 'unused'.
It will not be possible to recover data from this kind of operation.