Do a anti virus just identify the viruses and Trojan?
Only, if the virus information is known and the AV applicaton is updated.
Then you have to buy a program to remove the viruses and Trojan?
No, you don't. However, as Ken Blake mentioned, there are cases where an AV
scanner may be ineffective and a clean re-installation is required.
Real-time AV applications - for viral malware.
Do not utilize more than one (1) real-time anti-virus scanning engine!
Disable the e-mail scanning function during installation (Custom
Installation on some AV apps.) as it provides no additional protection.
Why You Don't Need Your Anti-Virus Program to Scan Your E-Mail
http://thundercloud.net/infoave/tutorials/email-scanning/index.htm
Viral Irony: The Most Common Cause of Corruption.
http://www.microsoft.com/windows/IE/community/columns/filecorruption.mspx
Avira AntiVir® Personal - FREE Antivirus
http://www.free-av.com/
You may wish to consider removing the 'AntiVir Nagscreen'
http://www.elitekiller.com/files/disable_antivir_nag.htm
or
Free antivirus - avast! 4 Home Edition
It includes ANTI-SPYWARE protection, certified by the West Coast Labs
Checkmark process, and ANTI-ROOTKIT DETECTION based on the best-in class
GMER technology.
http://www.avast.com/eng/avast_4_home.html
(Choose Custom Installation and under Resident
Protection, uncheck: Internet Mail and Outlook/Exchange.)
or
AVG Anti-Virus Free Edition
http://free.grisoft.com/
(Choose custom install and untick the email scanner plugin.)
and (optional but highly recommendable)
On-demand AV applications.
(add them to your arsenal and use them as a "second opinion" av scanner).
David H. Lipman's MULTI_AV Tool
http://www.pctipp.ch/ds/28400/28470/Multi_AV.exe
http://www.pctipp.ch/downloads/dl/35905.asp
English:
http://www.raymond.cc/blog/archives/2008/01/09/scan-your-computer-with-multiple-anti-virus-for-free/
Additional Instructions:
http://pcdid.com/Multi_AV.htm
--and/or--
BitDefender10 Free Edition (*NOT FOR VISTA*)
http://www.bitdefender.com/PRODUCT-14-en--BitDefender-8-Free-Edition.html
--and/or--
Kaspersky's AVPTool
http://downloads5.kaspersky-labs.com/devbuilds/AVPTool/
There's no updating involved since the scanning engine is updated
several times a day and you simply download the updated scanner whenever
you want to do a scan.
A-S applications - for non-viral malware.
The effectiveness of an individual A-S scanners can be wide-ranging and
oftentimes a collection of scanners is best. There isn't one software that
cleans and immunizes you against everything. That's why you need multiple
products to do the job i.e. overlap their coverage - one may catch what
another may miss, (grab'em all).
SuperAntispyware - Free
http://www.superantispyware.com/superantispywarefreevspro.html
and
Ad-Aware 2007 - Free
http://www.lavasoftusa.com/products/ad_aware_free.php
http://www.download.com/3000-2144-10045910.html
and
Spybot Search & Destroy - Free
http://www.safer-networking.org/en/download/index.html
and
Windows Defender - Free (build-in in Vista)
http://www.microsoft.com/athome/security/spyware/software/default.mspx
WD monitors the start-registry and hooks registers/files to prevent spyware
and worms to install to the OS.
Interesting reading:
http://www.pcworld.com/article/id,136195/article.html
"...Windows Defender did excel in behavior-based protection, which detects
changes to key areas of the system without having to know anything about
the actual threat."
And:
Routinely practice Safe-Hex.
http://www.claymania.com/safe-hex.html
Hundreds Click on 'Click Here to Get Infected' Ad
http://www.eweek.com/article2/0,1895,2132447,00.asp
Good luck