Choosing and Installing an Antivirus Client

Antivirus software works primarily by comparing the contents of the computer with a list of known viruses (virus definitions)


Software vendors sometimes bundle security software, including antivirus and firewall products, that can install on top of the existing Windows solutions. Overlapping security programs that perform the same function, when installed at the same time, can cause conflicts and unpredictable results. You don't want two firewall programs, for example, operating concurrently. You can select which firewall to run in Action Center or, if you choose to use the built-in Windows Firewall, simply uninstall the secondary firewall using Programs and Features in Control Panel.

to see whether any part of a computer is infected. It does this in two different ways. The first is by scheduling recurring scans, daily or perhaps weekly at a time of your choosing, during which the program plods through all endangered areas of the computer. If any viruses are found, they can be cleaned, deleted, or rendered inert, effectively stopping the virus from spreading. Several prominent companies offer antivirus scans of this type for free on their websites. This cleaning approach works magnificently in some cases. In other cases, after a computer is compromised, cleaning a virus is like trying to push a bullet back into a gun.

Viruses are best detected and defeated before they infect and damage a computer, which is why web-based scans alone are not enough. Real-time protection is the second major feature of modern antivirus programs, and the one that's worth money. With real-time protection, computer activity is constantly monitored. Whenever a file is read, opened, or modified, it is checked against the list of known viruses. With this level of protection, a virus can be identified and stopped before it can spread or cause any damage, and that is a valuable service indeed.

Most modern antivirus programs provide both scheduled scans and real-time protection, but both features are only as good as the list of known viruses they can identify. Virus writers are an active bunch, and using an antivirus program with an outdated list is not much better than running nothing at all.

When a new virus is detected in the wild, antivirus vendors race to identify and capture its unique signature. Only then can the vendor's virus definition lists be updated and distributed to customers, so in addition to the quality of the software itself, the experience and knowledge of the response team is of paramount importance. Good antivirus vendors deliver timely and effective virus definition updates, so seek a vendor with a proven record of responsiveness. The heavyweights in the industry are McAfee, Symantec, and Trend Micro, but a number of well-respected smaller vendors do a fine job, some of whose products might be a better alternative.

If you subscribe to a high-speed Internet service, it's likely that your provider will supply you with an antivirus program free of charge. Although ISPs are in general an outstanding bunch, their generosity is far from altruistic. ISPs provide free antivirus programs because if they don't, unprotected systems can bog down their networks, erode trust in their service, and cause a string of headaches. Many hackers first go for easy targets, and an unprotected system on a public network is soon mincemeat or, worse, can be used as a launching pad for further attacks.

If your ISP provides free antivirus protection, the ISP usually has done the homework to select a reputable vendor and can often provide some level of support for that product. You may cross the margin of diminishing utility by paying more for a different antivirus program, so unless you have a specific need, try your ISP's recommended antivirus software if you don't already have some installed.

If your computer manufacturer offers none, and your ISP doesn't either, you might need to buy antivirus software yourself. This might seem challenging at first glance because there are so many features to consider and product lines change frequently. For advice on antivirus software, consult reputable periodicals


The antivirus business is a 2 billion dollar market, where the initial cost of a software product is quickly outweighed by costs for recurring subscription services for updates. When selecting a product, consider yearly subscription costs over the expected life of your computer. Multiyear subscriptions may provide valuable discounts, but as competition increases, subscription prices may drop.


We get no kickbacks for unsolicited advertising in our books (too bad), but we're occasionally moved to give tips to readers about products we like a lot. One of these is Avast! antivirus. For individual users, the price is right—it's free. What's more, it's easy to use, doesn't drag down my system speed as some other antivirus programs do, and it's a real-time virus scanner that protects against malicious code cloaked inside IMs, emails, web browsing, network communications, P2Ptrans-fers, web pages, and downloads. For more information, visit

such as PC World or PC Magazine, both of which maintain up-to-date information on their websites. You might also want to check out Virus Bulletin at It's great when viruses are stopped before they get a chance to take root, but sometimes they're uncovered only after the damage is done. The primary job of your antivirus software is to detect and prevent viruses. Most programs can clean and repair simple infections, but more complex and destructive viruses require separate, specifically designed removal tools. If you're not careful, even if a virus is successfully cleaned, reinfection can occur the second you lift your finger from the mouse button. Regardless of which software protects your computer, here are the steps to break the cycle and get rid of a virus effectively:

1. Manually run Windows Update to fix any new security vulnerabilities in Windows. To be thorough, also check vendors' websites for updates to any additional software you may have installed. Remember, if you remove a virus but remain vulnerable to a relapse, you might be in for a long day.

2. Update your virus definitions to detect the latest threats. Most antivirus software uses definition files that become stale quickly. Don't bring a knife to a gun fight.

3. Run a virus scan to find and eliminate any viruses. If you clean or quarantine a virus this way, run a follow-up scan to make sure it's truly dispatched. If not, at least you have identified the name of the threat and can proceed to the next step.

4. Visit your antivirus vendor's website and search for the identified threat. Most likely they have instructions and tools to help remove the virus from your computer. After a removal attempt, run another scan to confirm success. If needed, a general web search can often reveal alternative methods of treatment.

If all else fails, the fifth step to virus removal is tried and true: reinstall Windows from scratch. Make sure to delete and re-create the hard disk partitions during the install, and pat yourself on the back for having a recent backup of your critical data.

^ For detailed instructions on reinstalling Windows 7 from scratch, see Chapter 2, "Installing and Upgrading Windows 7."

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