Helping people with computers... one answer at a time.
Computer viruses are a fact of modern, internet-connected life. At best, they're annoying performance sucking beasts, but at worst ... kiss all your data good bye.
We all need to take steps to make sure that our computers are safe, or we risk infection. Complacency is not an option.
And yet, even after all the news, and all the warnings, and after all this time ...
complacency remains all too common.
There are four important steps:
1. Install and Run an Anti-Virus Program
There are many out there.
Personally, I run Computer Associate's eTrust AntiVirus. It was the corporate standard solution where I used to work, and has served me exceedingly well for several years now. I have it scheduled to update signatures and scan every night.
I've also heard good things about Panda Antivirus, AVG Anti Virus, and Kaspersky Anti-Virus. Norton AntiVirus, now owned by Symantec is also very popular. In particular, Symantec maintains one of the best reference sites for virus related security issues.
Free and On-Line Virus Scanners: I've learned that not all virus scanners catch all viruses. I recommend having a selection of free virus scanners to run as a "second tier". AVG has a free product. Trend Micro's Housecall, and Panda's Active Scan are on-line scanners that download as an ActiveX control in your browser. Most downloadable virus scanning solutions often include free trial periods that can also come in handy as one-time second-level scans.
Download and install the package of your choice. Now. Before you forget.
2. Update the Anti-Virus Database
Your first step should be to update the virus signature database that came with the installation. New viruses are being created every day, and the databases that the anti-virus programs use are being updated as well. You need to get the latest database for your program right away.
Most of the programs have update functions that will locate, download and install the latest databases automatically. Make sure that this is enabled.
3. Run Regular Scans
Most of the anti-virus programs work automatically. Once installed they are configured to scan all incoming and outgoing files, and often hook into your email in some way to double check that your received email is clean as well.
Unless you know what you're doing, make sure that this "real time" scanning is enabled.
I also recommend periodically running scans of your hard disk(s). Certainly when you first install the software you should run a full scan. Then, depending on how heavily used your machine is, you should run a scan periodically as well.
Some programs will allow you to schedule such a scan to happen automatically. In my case, for example, since my computers are on 24 hours a day, I schedule full virus scans nightly, while I'm asleep.
4. Keep Windows Up-To-Date
Visit Windows Update regularly, or simply enable the automatic update feature in Windows XP.
All software has bugs. Some of those bugs are used to create the exploits that virus writers take advantage of to create viruses that can infect your system. As these bugs are found, Microsoft fixes the affected components in the operating system, and makes those fixes available for download and install using Windows Update.
The "problem", is that even once the bugs are discovered and publicized, and even when the fix is available, virus writers get busy writing viruses that still exploit them. Why? Because they know not everyone stays up-to-date. (As an example, one of my most popular articles here on Ask Leo! is being read by thousands of people each month who are still being affected by a virus using an exploit that was patched close to two years ago.)
Keep Windows up-to-date. Let someone else have the "fun" of being infected with the latest viruses. Visit Windows Update weekly, or enable automatic update.
Sadly, there is no "best" anti-virus program. Each may miss some something that the other's catch. That's one of the reasons I list several. The best advice is to use one, any one, and have the others "on call" for those cases when spyware sneaks past the one you use regularly.
If you do install more than one package, you should not enable the "real time" scanning for more than one at the same time - they will conflict with each other, and will cause unpredictable results.