You can also use Comodo, it has a great firewall and it's virus isn't at that level yet but it may be fine for you. However, the firewall is really intrusive and gives you lots of pop up alert. Wouldn't recommend this unless you're knowledgeable and understand what's the firewall trying to do. Nevertheless, here's the link to it: http://personalfirewall.comodo.com/free-download.html
It's a free full security suite.
The above posts are great free solutuions. But if you really want BEST, its Webroot Spyware with Anti-virus, or PCtools Spyware Doctor with anti-virus. I prefer Webroot among these two, and I prefer a free solution over a paid one. After all, all I do with my windows machine is play games, and ocasionally browing safe sites, like amazon.
For "suspicious sites", consider installing Linux, its free and very easy to dual-boot