Do you think your infected with malware and don't have money to buy security software to help get you out of a jam? I have had many users over the years that have had luck going to the following security websites below:

Housecall's (Trendmicro's Free Security tools page)

Free Prevention Tools to help you stay clean and secure

http://free.antivirus.com/prevention-tools/

5 Free Tools to help regain control of a compromised computer.

   http://free.antivirus.com/clean-up-tools/

Housecall

Hijack This

RUBotted

CWShredder

Rootkit Buster

Another company that is proactive when it comes to producing free security tools is Sophos, they have one of the more extensive list of free security technologies to help:

http://www.sophos.com/en-us/products/free-tools.aspx  

Another online based scanner is @ F-Secure

Depending on the type of infection, some scanners fail to work correctly and having a second choice is key:

http://www.f-secure.com/en_EMEA/security/tools/online-scanner/

On another computer because it won't boot? Here is your free Rescue CD From F-Secure:

http://www.f-secure.com/en_EMEA/security/tools/rescue-cd/

The Rescue CD PDF instructions document:

http://www.f-secure.com/linux-weblog/files/rescue_cd_user_guide.20090717.pdf

Anti-Virus Software

Microsoft also has a Anti Virus Scanner "on demand" that is a single .exe file that runs in RAM to scan the systems fixed hard-drives.

http://www.microsoft.com/security/scanner/en-us/default.aspx

http://fileforum.betanews.com/detail/Malwarebytes-AntiMalware/1186760019/1

Below are some other resources to help you stay secure:

Application security update scanner and also a vulnerability scanner all in one. This application patches software on your computer:

 Secunia Personal Software Inspector (PSI)

http://secunia.com/vulnerability_scanning/personal/

 Below, check and see what computer ports may be open without your knowledge. These ports can communicate remotely and send data to unauthorized people and computers all over the world that have rogue itentions.

 https://www.grc.com/x/ne.dll?bh0bkyd2

Another online based scanner is @ F-Secure

Depending on the type of infection, some scanners fail to work correctly and having a second choice is key:

http://www.f-secure.com/en_EMEA/security/tools/online-scanner/

On another computer because it won't boot? Here is your free Rescue CD From F-Secure:

http://www.f-secure.com/en_EMEA/security/tools/rescue-cd/

The Rescue CD PDF instructions document:

http://www.f-secure.com/linux-weblog/files/rescue_cd_user_guide.20090717.pdf

A great site for dealing with Spyware and other Windows Parasites is @

http://www.mvps.org/winhelp2002/unwanted.htm

You will also find many other cool security related material there and free tips. He has been helping Clean Up the Internet Community for years and is a Microsoft MVP.

Microsoft Baseline Security Analyzer 2.2

http://technet.microsoft.com/en-us/security/cc184923

Bot Hunter

http://www.bothunter.net/

BotHunter is the first, and still the best, network-based malware infection diagnosis system out there.  It tracks the two-way communication flows between your computer(s) and the Internet, comparing your network traffic against an abstract model of malware communication patterns.(1)  Its goal is to catch bots and other coordination-centric malware infesting your network, and it is exceptionally effective.

XArp

XArp is a security application that uses advanced techniques to detect ARP based attacks. ARP attacks allow an attacker to silently eavesdrop or manipulate all your data that is sent over the network. This include documents, emails and VoiceIP conversations. ARP spoofing attacks are undetected by firewalls and operating system security features: firewalls don't protect you against ARP based attack! XArp has been developed to target this problem: it uses advanced techniques to detect ARP attacks and thus helps you to keep your data private.

http://www.chrismc.de/development/xarp/

File Integrity:

http://www.karenware.com/powertools/pthasher.asp

Additional FreeTools for advanced users, when it comes to dissecting a compromised system is Sysinternals @

 http://technet.microsoft.com/en-us/sysinternals/bb842062.aspx