do i need antivirus if i have windows defender
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.)
or
ESET NOD32 Antivirus - Not Free
http://www.eset.com/
or
Kaspersky® Anti-Virus 7.0 - Not Free
http://www.kaspersky.com/homeuser
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
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.
Dr.Web CureIt!® Utility - FREE
http://www.freedrweb.com/cureit/
Malwarebytes© Corporation - Anti-Malware
http://www.malwarebytes.org/mbam/program/mbam-setup.exe
Note: It is Free for private use. Just download (do NOT buy) and install.
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."
After the software is updated, it is suggested scanning the system in Safe
Mode.
A clarification on the terminology: the word "malware" is short for
"malicious software." Most Anti-Virus applications detect many types of
malware such as viruses, worms, trojans, etc.
What AV applications usually don't detect is "non-viral" malware, and the
term "non-viral malware" is normally used to refer to things like spyware
and adware.