Ad-aware Home Page (Removes Ad-ware and Spyware Programs) Free Download - Free to Use (non-commercial)

For information on using and updating Ad-aware see this article.
 

NoAdware.net Homepage (Adware, Spyware, Dialler, and Web Bug Scan) Free Download - Must register to remove adware.

Microsoft Defender (was MS Antispyware)

Microsoft Defender (currently in Beta release)  Download  Free Download - Free to Use

Spybot Homepage The home of Spybot-S&D, the best (according to PC World, PCMag.com, Download.com...) privacy software available!

All about Malware including Adware, Spyware, Trojans and Key loggers

The Spyware Guide was created to provide an all inclusive and updated resource on spy ware applications, what they do and how they’re used.
 

Malware

There are many forms of programs that may be installed on your computer you may not wish were there. These are commonly and collectively known as Malware.

Viruses, adware, key loggers, spyware and trojans are obvious examples but there are other program types that can also stop your computer from functioning as you wish it to.

The definitions below come from www.spywareguide.com an excellent resource covering Malware programs.

 
If you have detected any malware on your computer using programs such as Ad-Aware, you may find out more by using Spyware Guide's search engine.
 
 

 

Adware A program that creates advertisements on your PC. Note that many websites have their own advertising, unrelated to adware. Adware is any software application in which advertising is displayed while the program is running. The authors of these applications include additional code that delivers the ads, which can be viewed through pop-up windows or through a bar that appears on a computer screen and sometimes through text links or in search results. Adware may or may not track personal information. It may also gather information anonymously or in aggregate only.
Browser Hijacker Browser HiJacker Program that changes some settings in your browser. Commonly browser hijackers do one or more of the following:
  •  Changing your "search" page to pass all searches to a pay-per-search site
  •  Changing your default home page to the company page. Sometimes the software changes them to a portal featuring porn sites.
  • May transmit URLs viewed toward the company server
Browser Plugin Plug-ins are software programs that extend the capabilities of your Internet browser in a specific way. Not all browser plug-ins are harmful and some may be helpful. This category contains mostly dubious browser plugins such as "Search Assistant’s, toolbars etc. that have been known to transmit user data to their creators or to have been installed using covert means.
Bundled Software Bundled software is any software that is included, in addition, with other software. The bundled software is usually described in the EULA or license agreement - often not at the time of downloading. A popular example is Peer to Peer software that bundles additional software with their application in order to offset cost of giving the software away for free.
Commercial Keylogger Program designed to monitor user activity. May be used with or without consent. Because it is sold commercially, most anti-virus vendors do not detect it.
Commercial Network Management Tool Tools of this kind are mostly used in (large) corporations. They can log network traffic passively (sniffing) or examine the logs of proxies etc. Nothing is installed on the individual computers, the software runs on a central server, They can only log things that pass thru the network, not local things like entered passwords, keystrokes or screenshots.
DataMiner Software that's primary function is to gather data about an end-user. Some adware applications may employ data mining abilities.
Dialler A program that, often secretly, changes your dialup connection setting so that instead of calling your local internet provider, your PC calls are routed to an expensive 1900 or international phone number.
Generic Malware Generic category for all potentially unwanted software that secretly executes unwanted actions and/or causes system instability and/or uses an incredible amount of CPU cycles making it difficult for a PC to function normally.
LoyaltyWare A sub-form of adware. LoyaltyWare is a type of software that works around the concept of user loyalty by providing incentives in the form of cash, points, airline miles, or other type of goods while shopping.
Remote Administration Tool A tool that is intended to be used by network administrators to remotely control a PC on the network, usually for support or inventory purposes.
Due to the nature of the program, the possibility exists to be exploited for spying purposes.
Software Application Spywareguide fields many emails a day from key logging and malware vendors stating they've changed policies. After reviewing the software we confirm the changes claimed by the vendors and change the description to Software Application.
Trojan Trojan: aka Trojan Horse: A Trojan is a software program that enables an attacker to get nearly complete control over an infected PC. Frequently used by as a tool by malicious hackers. When this program executes, the program performs a specific set of actions, usually working toward the goal of allowing the Trojan to survive on a system and open up a backdoor
Utility Can be a small program, or set of small programs, that supports the OS by providing additional services that the OS does not provide. The nature of the utility is to provide users more functionality however some utilities have inherent privacy risks and users should carefully evaluate this trade-off.
Virus Malevolent software that spreads itself automatically by infesting other files on your PC. Software which attaches to other software. A boot virus inserts its code into the boot record or master boot record of a disk, so that when the machine boots from that disk, the virus code is executed. A file virus inserts its code into an executable file, so that when that file is executed, the virus is executed as well. A macro virus attaches itself to documents like Word or Excel.
Worm Virus-like program that spreads automatically to other computers, by sending itself out by email or by any other means. A program that propagates itself by attacking other machines and copying itself to the affected machine. Both worms and viruses are self-replicating code that travels from machine to machine by various means. Both worms and viruses have, as their first objective, merely propagation. Both can be destructive, depending on what payload, if any, they have been given. But there are some differences: worms may replace files, but do not insert themselves into files. In contrast, viruses insert themselves in files, but do not replace them.