As far as your Prevx slowing down the system a little, it's expected. You are talking about another program that is running along with the rest of your start up programs. It is a good firewall and I would not suggest not using it. You are more than welcome to try a couple of others, however, I use Prevx because it doesn't slow my system down as much as a few others that I tried. As far as your download sites, I don't know of anyone that has had problems with them. Just remember to run those scans at least once a week, if not twice. You will know if you need to run them twice by running one after you download some music. So all in all it sounds like your machine is running good again.