NOD32
It provides proactive detection against viruses and malware. It features on-demand scanning, and updates are in real-time. Additionally, it inspects SSL-encrypted communication channels too. It works fast and has lower system requirements when compared to leading AV software.
ESET NOD32 Antivirus v3.0 includes enhanced proactive scanning technology as well as improvements in removal of threats.
ESET NOD32 Antivirus v.4.0 includes smarter and faster protection. In addition, more proactive protection for computers and data against never-seen- before malicious codes or threats.
Costs:
- ESET NOD32 Antivirus v3.0 is $39.95
- ESET NOD32 Antivirus v.4.0 is $49.99

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Kaspersky
This anti-virus product is the better product. The 2009 version provides up-to-date protection, and screens users from Phishing and Malware sites. It offers real-time automated protection against current Internet threats. Additionally, it provides real-time scanning of email. The 2009 anti-virus product, then, provides complete antivirus protection from viruses and spyware, as well as from infected Websites. The KAV 2010 even got better by providing extra tools and features. This version provides essential PC protection (in fully automated real-time) at a price of only $39.95 (at kaspersky.com).
KAV 2010 improvements include identity theft protection and blocking of suspicious programs based on their behavior. It also makes it simple for users to identify unsafe websites by color-coding them.
Note: Kaspersky Anti-Virus (KAV) 2011 is now available. It offers a number of new and improved features (check the site for details) for latest online threats. It carries the same price as KAV 2010 ($39.95) from the Kaspersky anti-virus site (http://www.kaspersky.com/kaspersky_anti-virus).
* Like with ESET NOD32, consider the 30-day commercial trial for Kaspersky too just to ensure you agree it has the better anti-virus protection. Otherwise, check out Buenaventura's article, "Kaspersky Antivirus 2011 Review" to see how she rates it.