hey, it depends on the O/s.
You may check this out:
Platinum Internet Security 2005
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Panda Software's Platinum Internet Security 2005 combines antivirus, firewall, and spam filtering along with its new TruPrevent Technology. Both AV-Test.org and ICSA Labs have tested the TruPrevent claims of behavioral, non-signature detection of new malware. And both have found the claims to be true. (TruPrevent Technology can also be purchased separately as an add-on to other antivirus protection).
PC-cillin Internet Security 2005
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Building on its solid antivirus capabilities, PC-cillin Internet Security 2005 includes spam and spyware protection, wireless device protection, firewall, privacy data protection, parental controls, and a year's free tech support via a toll-free number. The software automatically checks for new virus updates every 3 hours and the spam prevention includes a whitelist, blacklist, and Bayesian filter - all at a price substantially lower than many other antivirus suites.