Do NOT run two antivirus programs. (conflicts) ,But you have now Avast.
Thats 1. Number 2.A good realtime running Spyware program like
Super Antispyware or looking on Windows marketplace.
3 Spyware Blaster yes you need this in combination whit your AntiSpyware
Program.
4 Firewall,very importend for incoming and outgoing traffic.
You have enough choise,Kerio, Comodo,Sygate, and a few others.
Looking on
www.windowsmarketplace.com and you find something.