I used all kinds of free stuff and the first time I ran Prio I found that I was connected to two notorious hacker sites and I had Zone Alarm running. The first time I ran a rootkit finder [it only found them, did not remove them] I discovered all sorts of junk but the second time I ran it they did not show up, they were capable of detecting the rootkit finder software and hiding!! The simple truth is, with windows you will never know what problems you have, it is, by design, hackable. Unix and Mac OS's are by design a lot less hackable. Pick a free software firewall/anti virus name and research it well enough, you will find malware that it does not work against........
I've been repairing, programming and using computers since 1974 and to me, a windoz machine that is not behind a whitelisting SPI firewall is unacceptable and overdue for a rebuild from the ground up with a complete reformat. Leo LaPorte says pretty much the same thing.