I am running win7 and was running windows defender and the windows firewall. Is that good enough? I then started to run kaspersky 2011 suite in lieu of the aforementioned and was wondering if it really makes a difference? The resource usage with the windows defender was almost nil, but I couldn't help but think it was missing stuff that kaspersky would catch? I am most confused. Any help would be appreciated. Thanks.
You really want to run Microsoft Security Essentials which guards against viruses as well as other malware. Windows Defender is more limited and has been replaced by MSE. All the reviews that I have seen say that MSE is as effective as most of the commercial offerings and, as you say, it is extremely light on resources. It's good enough for me as the only defence (along with the Firewall).
I agree with ijack MSE is effective. But you can try yhis combo too.
Download & Install the following 3 freewares. It forms a free complete security suite for your system!
1. Avira Anvivir - http://www.free-av.com/en/download/index.html .
Avira is best & light solution for excellent overall system protection & internet security with real time updates, .