I'm considering buying Prevx1. I have a question. What exactly does it stop? Rootkits? Viruses? Spyware? Or what? I can't seem to get an impression...is it a HIPS too? I'm guessing it is, but what malware does it block? If I get Prevx1, I still need my firewall, right? And what about my other antispyware apps? I know I'd still need Antivir, and Spyware Terminator. But what abot Ewido, A-Squared, etc? What could I remove?