I'm average. I do like MSE's Zen-like simplicity. There's a lot to be said for being simple. I have tried Bullguard, Norton & McAfee in the past. There's way less to go wrong with simple IMHO. Well, I'm average but not 50+ & it is way perfect for me. It does work very well on Win 7 64 bit. However, the system tray icon hangs red at start-up sometimes. It is fairly rare though. I have read other people have had the same problem, I take it is a known bug. It works well on Vista as well. I have a lot of faith in it. Avast! free would almost certainly have been my second choice if MSE had proved to be troublesome. That's interesting. I wonder why it slows XP?