Reading tens of threads for a couple of days might have convinced me to go for one of these solutions. To be honest they were completely new to me a week ago (I know ...). I read much about their functioning, and I have to say it was very interesting and instructive. Now my sole concern is about their slowing down my laptop or not. If any one of them was very light (+ Opera, NOD32 and Outpost friendly), my choice would be much easier. Therefore, I am afraid I have to seek advice from experts. Thanks a lot for your help !