If we have anti-virus software installed on our computers (and it's my guess that many of those who do don't have their virus definitions updated because they're using pirated copies of the software that are no longer performing automatic updates) it's very easy to set our systems to run a weekly check. I prefer that this take place at night, because in my case we're talking about well over two hours of computing time, but I suppose that finding the best time to run a check really isn't difficult. And yet I'm also convinced that no matter how many times we've been told that we should run these checks weekly, all too few of us actually do.