I've been using My e-Trust from Computer Associates for several years since they took over VET which I had previously been using.
Only once in that time has anything managed to sneak through. The files update automatically whenever there is something to download, I have it on two lappies as well as my desktop, and it costs about $A25 per year (10 quid) for almost absolute peace of mind.
BUT. Their service is a nightmare unless you upgrade. If anything goes wrong you are thrown off into the Knowledge- whatever-it-is and good luck. Just received a Vulnerability notice by email, which only affects W2000 upwards. Downloaded it anyway on to my 98SE desktop with no problems, but trying to get it on to my lappies? Fergeddaboudit!
If you have problems, click here. What's your username? Don't have one? (yes, I do) no problems, register here. I register again. Please help. Sorry don't know that user name. Goodbye.
Despite the fact that I've been delighted with it for years, the impossibility of getting a simple question answered means I'll probably be looking around for a new solution next renewal time.