I've used Semantec, Grisoft's AVG, and Panda AV apps. None of those have been satisfactory. They all tend to use too much system resources, or cause other problems. Currently, I'm using Panda AV, but it is causing start up problems and it seems to have a mind of its own WRT running scans. On the firewall front, I've used Zone Alarm Pro, but it slows my WinXP computer down. I've forgotten the names of the succession of other firewall apps I've used. Currently, the Panda AV app I'm using also provides a firewall. I'm not defenseless even without a firewall...