I think the consensus on this forum is to go with MSE for your anti virus. It's free, light weight, and works really well. Another security conscious decision would be to not use IE. Other than that I don't see a need to run anything else.
Hi thestud - There seems to be wavering opinions when it comes to antivirus software. There is a good thread to read about security written by The_Phophecy at the top of the Windows 7 Security discussion. It can also be found here - http://www.tomshardware.com/forum/7754-63-guide-prevent...
I'd also second Luser_'s comment and give another vote to Windows Security Essentials which is available as a free download from Microsoft.
I use a few different techniques including,Proxy servers, Microsoft Security Essentials, Firefox with Ad block plus and better privacy,and many others. I block my ip, use peer blocker, Configure win7 firewall, always scan files before opening, use my ISP for email to keep email off my PC locally, and make sure I do updates regularly while not downloading from sites or individuals that I suspect. Basically use a multi platform array of different techniques that work for you and what you do. Also, don't completely tell everything . lol