Install portable version of ClamWin anti-virus in a USB pen drive and scan your PC with it.
Use another clean PC to download Clamwin portable anti-virus and install it on a USB pen drive.
Download here http://portableapps.com/apps/utilities/c...
Document on how to configure ClamWin http://support.real-time.com/open-source...
1) Start Clamwin anti-virus and update the latest anti-virus definition files.
2)Select the tools menu bar, set the preferences to remove virus.
3)Start the infected PC in safe mode by pressing F8 during start up.
4) Run the Clamwin Anti-virus that is installed on the USB pen drive to scan the
infected PC.
5)After removing the virus, install crap cleaner (ccleaner) to get rid of the
viruses left over setting in the windows registry.

You should choose the one which will be the best and the handiest for you
“How to choose the right security tool (antivirus, antispyware, firewall or security suit)
If you decided to install a security tool to protect your computer you have several options. You can choose between firewall, antivirus, anti-spyware and a security suite which includes features of all the mentioned.
Antivirus software is computer program which detects, neutralizes or deletes malicious software. Originally this type of program was called that way because it was supposed to fight only computer viruses. Nowadays these programs combat various types of malwares, trojan horses, worms, adwares and other computer parasites.The very first antivirus program was created in 1988 by Dirty House productions.
Normaly antivirus program uses two different techniques to detect and then eleminate malwares. It can scan computer files to find viruses matching its virus definition database or try to identify …”

I have used AVG Anti Virus, Zone Alarm Firewall, Spy-bot Search and Destroy a spyware killer for years. I have recently added superantispyware. They are all free for personal use and I have had no trouble with Viruses Trojans Hackers etc. I have just upgraded to AVG free 8.0 and all seems good so far. Zone Alarm allows a lot of personal configuration unlike the Windows Firewall. They can all be downloaded from http://www.download.com/ I also use Windows Defender from the Microsoft site. It is safe to use two anti-spy products but never use more than one A/V as it can cause conflicts. You should run A/V and anti spy weekly. Hope this helps

ESET NOD32 Antivirus, 30 days trial http://www.nod32.com.sg/html/44/42/
ESET NOD32 Antivirus is the best antivirus in the market. It requires less memony and CPU power, running very fast, not like other antivirus system, slow down your computer, so you no need to disable the function when you play game or watch movie.
ESET NOD32 Antivirus can detect and block unknow virus!
AV-Comparatives named ESET the “Best Antivirus Product” the last two years as they know it’s proactive, precise technology—not brand names—that stops malware. And ESET NOD32® Antivirus is the best virus protection available.

1. You have the Grisoft’s AVG Free Edition downloadable from
http://www.grisoft.cz/filedir/inst/avg...
2.Avast gives free license to home and non commercial purposes
which is downloadable from
http://files.avast.com/iavs4pro/setupe...
for registration visit
http://www.avast.com/eng/home-registra...
3.Free Antivirus from Avira
http://www.download.com/Avira-AntiVir-...
4.Comodo free antivirus visit
http://antivirus.comodo.com/
thats it!

Download and install Avira / PC Tools Antivirus.Both of them are free
Combine it with an antispyware and you will have complete protection for your PC.I suggest you try Spyware Doctor or Spyware Blaster.(You can even try free firewalls like Zonealarm and Comodo )

http://www.grisoft.com/ww.product-avg-internet-...

Hi
I suggest you read this review:http://www.techsupportalert.com/best-fre…

The only thing the free ones do is remove coookies thats it till you pay otherwise your computer will crash soon.

AVAST – free, and ranked in the top three – often #1.

These are all free