All suppliers issue new updates as new threats become apparent.  Reputable firms issue these every few hours and enable protection from fast spreading worms, trojans and diallers.  Check that your last update is less than a day old.  A full system scan could then be initiated if you feel particularly vulnerable.  Also check that you have the latest updates to Java, Flash (if installed), your PDF reader and other potential security back doors.

Make sure you have the latest version of your .PDF reader and whatever is used by default to display .JPG and other images. Any framework applets such as Java, Flash, Shockwave, Silverlight, and Air should be updated.  Any programs that enable messaging must also be secured - Skype, Trillian, AIM etc.  And if you download media - iTunes, Spotify, Winamp etc. 

 Optionally Remove Spyware/Adware

This is software that runs on your computer for the author’s benefit and at your cost.  It is delivered by many Web sites, file sharing programs, chat rooms and included in many CD-ROMs that come free with magazines.  The aim is usually to collect information about you with a view to targeting advertising to maximise sales.  Quite apart from privacy issues, this code will at best, degrade the performance of your PC, and often causes ‘legitimate’ programs to fail or give unexpected results.  Many Internet security suites include a degree of this type of protection, but sometimes not as complete as programs that target this type of threat solely.  Note that removing some malware may cause the delivering host program to produce unexpected results or fail. See example report produced for a recent client to see what harm some of these things can do.   See here for additional information.  Frequently used free removers include:

SUPERAntiSpyware	http://www.superantispyware.com/index.html
Spybot	http://www.safer-networking.org/en/index.html
Ad-Aware	http://www.lavasoftusa.com/software/adaware/
Anti-Malware	http://www.malwarebytes.org/mbam.php

Prevention is a good idea, two popular free programs that will help limit problems and should be confirmed to be updated are:

Microsoft Defender	http://www.microsoft.com/athome/security/spyware/software/default.mspx [included with Vista]
Spyware Blaster	http://www.javacoolsoftware.com/spywareblaster.html)

Delete temporary files, browser cache & trash

These files waste space, and slow file access and therefore negatively impact system performance.  There are numerous free programs to help with this, such as CCleaner  (http://www.ccleaner.com/)

Take and verify Backups

Sooner or later, all hardware will fail.  Also, despite taking all reasonable precautions many people fall foul of malicious code or install software incompatible with their computer.  In such situations having a second copy of your favourite photos, address book entries or secret password document will save a lot of anguish and money for data recovery.  This is a good time to either make a backup copy of important files or check the log files of an automated backup regime.  Also, try to restore a test file to confirm that the backup is sound and you remember how to do it.  Please see my Guide to Backing up Computer Files.  For Windows 8 systems consider refreshing the system image from the command prompt by running RECIMG

Ensure Surge Protection is Effective *

If you have already received a spike you may not notice that your equipment is unprotected unless you check that the appropriate LED is still illuminated.  Often an amber LED indicates that power is connected, and a green LED is illuminated if your appliances are protected. If there is no green LED then you have taken an electrical hit large enough to cause the surge protector to save you - there is no further protection until you replace the surge protector or fit an uninterruptible power supply (UPS).  If you have a UPS already - test it.

Clean filters *

If you were wise enough to pay a little extra when buying your PC and have one or two removable air filters included, this would be a good time to remove and vacuum them to prevent dust limiting the effectiveness of your heatsinks.

Hard disk error check

By resolving logic errors now, future corruptions may be avoided.  Access via Windows Explorer, right click the device, Properties, Tools tab, Error Checking. Tick the first checkbox only to run the 3 phase repair.  If you have a constantly running program that reports on the SMART parameters such as GSmartControl or Acronis Drive Monitor, check it to ensure the health is still good.

Clean print head *

Locate password reset disk & recovery notes *

To ensure that you can not be locked out of your own computer, ensure password reset disks are prepared and accessible as explained at http://support.microsoft.com/kb/305478 for Windows XP or here for Windows Vista. Recovery notes will be invaluable when the computer has to be repaired.  Include usernames/passwords for any important websites, product activation keys, location of installation CDs, e-mail account details (username, password, server addresses & configuration details), name of e-mail and address book clients, ISP authentication credentials.

Defragment system volume (Not Solid State Disks)

By making all files contiguous, disk reads are minimised as split I/Os are avoided and performance therefore improved.  For Windows XP do this via Start, All Programs, Accessories, System Tools, Disk Defragmenter.  For Vista and Windows 7 you can easily set this to happen automatically.  Note that electro-mechanical disks (80% of those running today) always benefit from this but hybrid solid state disks should only be defragmented infrequently.