What considerations are important when using multiple anti-virus programs?

I understand that they cannot be running simultaneously. But under what circumstances can they be co-resident (installed), and under what circumstances must all besides the current one be uninstalled? (Or turned off, or disabled???)

thanks,
richard myers
Denver, Colorado

You should not have more than one antivirus configured for resident (on-access) scanning at the same time. You should use no more than two AVs, and you should use one as your primary (resident/on-access) scanner and the other as a backup non-resident/on-demand scanner. Some antivirus programs (like Kaspersky) will tell you to remove any other AV software on your computer upon installation--even if the other AV is nonresident. You may be able to ignore this without any problems, but if you are advised to remove the other AV, you should do so. Even if nothing "bad" happens, the AVS can tend to get in each other's way.

As for considerations, if you want to use two AVs, it's a good idea to pick two that compliment each other. For instance, AntiVir and NOD32 have pretty good heuristics, also AVG and Panda. F-Secure and Trend Micro are pretty good at detecting rootkits. Kaspersky is pretty good at unpacking. McAfee, Microsoft, and Symantec have low false positives and are pretty good at "curing" any infection they spot. Finally, Clam/ClamWin doesn't have any fancy heuristics, but it has hard-working analysts that produce frequent signature updates.

There is an informative "grading of AV products at https://www.sunbelt-software.com/ihs/alex/Results_2D2008m3b_US.htm on the Web.

Regards,