For those of you who have Windows systems and use Microsoft Security Essentials for background virus detection, MS recently released MSE ver 2. Better engine and a few other improvements. For more details, surf:
If wondering, I installed MSE ver 2 on my current HP DV7 17.3" laptop (using Win 7) and it seems to work great. From a GUI view, it looks and feels the same as its version 1. I also noticed that ver 2 allows selectable CPU usage ratio during its full scan tasks. For example, while scanning, your can configure it to only use 20% of CPU. Thus, leaving 80% CPU for parallel applications. A cool feature that previous ver 1 didn't offer.