The title sums it up, pretty much. I tend to arrange windows on the screen manually, and when I bring a window too far up it automatically maximizes itself. How do I turn this off? It drives me nuts!
Here are step by step instructions from How-To Geek, "Disable Aero Snap."
Short version: Go to the control panel -> Ease of Use Center. Click "Change how your mouse works". Un-check “Prevent windows from being automatically arranged when moved to the edge of the screen” and hit Apply.