Dr Web Antivirus is a Russian Antivirus that has been out for years.  The software is normally costs $35 dollars for a full version.  However, as of May 1, 2010 DR Web is offering a free license key if one completes a 3 minute survey.  The instructions can be found on this webpage.

    Get the free DR WEB 32/64bit License Key here

   The offer is for 32 bit and 64 bit versions and includes rootkit, antispyware, firewall, and antivirus protection.  The software even supports Windows 95 through Windows 7.  The antivirus also includes an internet link check to prevent phishing websites.  Finally, the software is extremely lightweight and only needs 40 megabytes for the antivirus engine and an additional 9 megabytes for the firewall.  Therefore, the computer will performance will not be affected even on lesser equipped system.