From AVAST Software:
Avast Home Edition is free antivirus software for home, non-commercial use. It scans for viruses, worms, and Trojan horses. Avast scans on demand - with skinnable simple interface, during boot time, and on access. It protects e-mail, ICQ, mIRC, Kazaa. It maintains virus chest. True incremental updates (well under 100KB) based on iAVS technology update virus definition at least twice a week. Version 4.1.389 includes improved archive operation, support for Windows XP SP2 Security Center and it's available now in English, Czech, Dutch, French, German, Hungarian, Italian, Japanese, Polish, Portuguese, Russian, Slovak, and Spanish languages.
Note: Users should register at the developer's site to obtain the free license key.