Copied from an Antivirus shootout from Winmag:
InoculateIT was the second worst at finding viruses, catching only 90.7% of them.
Starting a scan is done either by right-mouse-clicking a file in the Explorer and choosing "check viruses" (which almost every other program offers as well), or by doing essentially the same thing in the InoculateIT window. No pre-set "quick scans" are configured, or even possible. There is no provision to schedule scans at night, but you can manually use Window's own scheduling program if you're feeling ambitious.
Not surprisingly, InoculateIT has no provisions to check for downloaded or emailed viruses, and thus it let them come through without complaint. Executable viruses were caught when they were saved to the hard drive as files, but ZIP files weren't. Script viruses that can email themselves weren't caught even when they were running.
Though InoculateIT caught more viruses than the other free product in this review, spending a few dollars for more complete protection is probably worth it.
Complete Review
I have used used many different Antivirus programs, and the best one that I have tried and currently use that is not a resource hog, and has worked well (actually caught a few Trojans and Viruses on my system that Norton, AVP, Panda and others did not) is PCcillin.