SECURITY

The following applications do an excellent job of cleaning up extraneous files, spyware, and viruses in Windows. These freeware versions do not
usually scan at user-defined times (the paid versions do). It is better to run them one at a time, preferably in the SAFE MODE, but I have not (yet)
encountered problems with running them concurrently overnight as an administrator and in the regular mode.  Before running them open them with
administrator priveleges and click on Update icons  (paid versions usually update automatically). Because automatic updates can interrupt what
you are doing I  recommend  that you deselect automatic updating where possible. Purifying an entire computer will typically take several hours
and I therefore run them simulataneously overnight . DO NOT INSTALL MORE THAN ONE ANTI-VIRUS PROGRAM - otherwise they will interfere
with one another and, at best, slow down detections.

REVO UNINSTALLER
Deletes detritus left over by sloppy or nefarious programming. I liked it so much I bought the paid version (ca $55 for 3 computers),
BUT THIS APPEARS TO BE A SCAM - when installing the purchased version the supplied registration number is never
asked for (but it may include extra features that, if so, should have been indicated when updating). Apparently you pay $55 and get the same product
as the free version, with continued messages asking you to "upgrade" to the paid "pro" version.

MICROSOFT SECURITY ESSENTIALS
Apparently excellent and (remarkably) unobtrusive. But ZONE ALARM  is probably better.

AVAST ANTI-VIRUS 
Recommended by Consumer Reports.

ZONE ALARM
A superb firewall plus anti-virus package.

CCLEANER
Cleans out unnecesary files, browser cookies, etc. Also the only reliable registry cleaner I have encountered. You should repeat executions
until nothing changes (MS Internet Explorer files are especially stubborn).

SPYBOT
Allows immunization against known spyware. In my experience it catches the most malware of any of the apps.
If you insist on just one malware removal app, this is the one.

RKILL
Stops Malware running to allow its removal. Can be run less frequently than those above.

TDSSKILLER
Removes specific rootkits. Can be run less frequently than those above.

SECURITY TANGO (Windows, Linux, Mac)
An orchestrated sequence of tasks to rid your PC of the most persistent malware. Print out the list of instructions
before using. This site also contains links to much freeware. However, the red-underlined links above to security apps
will  remove most malware.