I do run AVG, but I no longer run a software firewall (besides the Windows one). I have my Linksys router with a Linux-based WRT firmware, and that should provide very good protection from outside threats.
I also don't run any Spyware protection apps anymore. Basically, I decided that I was only going to use trusted apps, so the only things I install are either open-source apps, Microsoft Apps, and games from Steam. I don't download any movies/music/software from the internet, and I run Firefox with Adblock, NoScript, and SecureLogin. Because of NoScript I am unlikely to get a drive-by infection, and I don't download miscellaneous crap to get a trojan. As a result, my system is as fast now (6 months after installation) as when it was first installed... which is uncommon for Windows, to say the least.