I've been paying 25e per year for F-Secure and been quite happy with it. Last time when I got a suspicious post I could see how fast it got recognized by that software - it took some 4 hours and it was added to the database. There are good scanners in the net if you get something suspicious. A couple of times I got an infection from some website - and they weren't porn sites. S#it happens sometimes - but never caused too much trouble.