One of the more obvious features missing from all Windows incarnations (including Vista) is a 'snap' feature. The Appearance and Personalization section of the control panel should include an option that allows windows to snap to each other, screen axes, and screen edges. The need for this feature only increases with wide screen and multi-monitor environments.
Ivan Heckman ran into this inconvenience, too and decided to do something about it. He created a free utility called allSnap that does all of this and more. Check out his site for more information and a video demo.