@tw0rld: Not having an antivirus running doesn't mean not having an antivirus installed to manually run scans (although that wouldn't matter that much anyways). No single antiviruses is fireproof. There are many other much more important steps than having an antivirus on your computer that is not guaranteed to even detect the virus. Which leaves you in the same situation "my computer is clean because my antivirus didn't find anything"...
People who get viruses will find a way to get a virus past their antivirus anyways.
It's really just commonsense. If you don't know to set your computer to show all file extensions, and to never run an executable that you're not entirely sure is safe... odds are you're going to get a virus. I'll explain how I remain virus free.
1. Use Firefox (names of extensions in brackets)
a) don't allow javascript unless you trust the site (NoScript)
b) block flash from auto starting - only allow if you trust the site (FlashBlock)
c) block ads (Adblock Plus)
d) block cookies (Cookie Monster)
e) (MD5 Reborned Hasher) compare md5 when download an application
2. Double check the URL any application was downloaded from (in case a site was hijacked, this takes two seconds to do).
3. If you're not 100% sure the application is safe:
a) check md5 and compare (if relevant)
b) submit to online virus scanners the following online virus scanners: Jotti, Virus.org, and Virustotal
c) submit to online sandboxes to receive an analysis report telling you what they do: Sunbelt Sandbox and Anubis
d) look at with FileAlyzer
e) check out with OllyDbg (advanced but extremely useful)
f) run in a local sandbox and monitor with Process Explorer
4. Run a Firewall that blocks all outbound traffic unless allowed.
5. Commonsense - don't download warez and blindly run these untrustworthy applications or games without doing what is written above. Don't use applications like Limewire. Don't fall for lame Facebook viruses... I probably do a lot more but I'm not thinking too clearly right now with a headache.
note: if you use Firefox with those extensions and you never download anything - then unless you harass some crazy hacker and become his target, I think you safe ;p
I scan my computer once a week just for the heck of it, I haven't had an infection in a decade. The last infection I remember was through something I downloaded on KaZaA when I was running Windows 2000 a few months after Napster went down. If you're really paranoid, get Deep Freeze and work in the cloud (or switch to Mac or a Linux Distro if you're willing to adapt).
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