Don't look any further than Microsoft's own free offering 'Microsoft Security Essentials' click here . It is a perfect integration with W7 and works flawlessly. I've used W7 since it's very early Beta's and only use MSE and the W7 Firewall and have had no problems over a very extended period. Why introduce 3rd party software when you can have MS programs that are a perfect answer. MSE is also very well reviewed by PC Advisor magazine.