Dr.Web Anti Virus for Windows Free Download
Shareware: You can try this program, but this version has some limited features or time usage restrictions. You should purchase it in order to remove those limits.
Exceptionally compact and fast anti-virus solution for PC. Multilevel protection of the system memory, file system all removable media against all types of viruses, rootkits, worms, trojans, spyware/adware, dialers and other malicious programs. Virus definitions automatic updates at hourly bases going up to twice per hour frequency at periods of high malware submissions. Basic AV functions (deep system/hard disk on-demand scanner, on-access 0-ring monitoring, highly-tuned mail-filtering) combined with proactive defense capabilities and new generation heuristic analyzer of Dr.Web anti-virus allow to “install and forget” about malware-related threats.
same as OS