Google is stepping up its efforts to improve computer security by adding warnings to users' search results when it suspects their systems might be compromised by a certain type of malware. Up to now, Google's security efforts have focused on the Chrome browser and the Android Market. These new alerts are not intended to be a comprehensive solution -- users must still be responsible for their machines' safety. "This is not a replacement for antivirus software," said Google spokesperson Jay Nancarrow. "... Users should install antivirus to clean their machines and protect themselves from other threats."