I use NOD32 4. It is actually one of the best antivirus/antimalware programs on the market.
It outperforms Avast and AVG (has a better detection rate, etc.,)
It has a feature called self defense (prevents malware corruption), System inspector for diagnostics of your entire computer, password locking of the settings, setting config backup, small resource footprint, the best hueristic detection ability of new and emerging threats with the lowest false positives (3 star certification), etc.,
Avast only recieved 1 star certification in testing (proactive/retroactive) for the ability to detect new threats (due partially to the high detection of legitimate programs as malware- i.e., false positives).
Most people do not understand the significance of Hueristic detection abilities and what false positives really mean- they are "wowed" by all the new "threats" their antivirus is detecting and cleaning, that no other program could find. Then, a few days, weeks later they wonder why Windows keeps crashing, programs dont work right, etc.,
Say a new Virus/trojan or worm is released. Hueristic detection is the ability of the antivirus to detect and block/remove that threat before your computer/network or data become infected and/or corrupted. New threats have no "definition" that alot of antivirus/antimalware products really heavily on. What that means is if a antivirus progam is lacking in hueristic detection abilities, your system becomes infected/corrupted because the antivirus program does not see it. Then after a definition is released, It then detects it and "quarantines" it. By then your data and computer may be so heavily corrupted/infected that the data is lost and a re-install of Windows is neccessary. If you are lucky no damage is done and your system just becomes part of a BOTNET. Trojans are now being designed to steal passswords/Account Numbers/Credit card and Bank info, they then send the data to remote servers for storage, and sometimes this info is sold on the black market. unusual bills, collection calls for past due accounts, or trouble with your tax return follow.
"false Positives" are just as bad. Say a Critical Windows or Program is "tagged" as suspicious and/or a virus or malware and the antivirus "deletes" or "cleans" it, that may result in corruption/instability of either Windows or the Program- this may result in BSOD's, etc.,
So, that is why an antivirus program with a high Hueristc detection ability, and the lowest amount of false positives (false detections) is ideal- it is this ability to acurately detect new threats that keeps your computer(s) secure. Avast is lacking in this.
For more info regarding Avast and Eset NOD32 see:
http://www.vistax64.com/system-security/172321-vista-sp1-antivirus-performance.html
If you are loking for a free good program go with Avira Antivir. it is on par with NOD32.
Is an AV on level with anything else, why the need for change? Cost you nothing and you got an almost full package.
Could also be in need of "better" firewall to stop certain programs from calling home.
