Speed Keys - Learn them and use them!
This is one of my favorite links at David Allen's web site. The amount of time you will save by learning these "universal" speed keys and keeping your hands on the keyboard can be significant. Of course, YMMV, depending on the kind of computing you do. A tremendous wealth of productivity tips, tools, and articles awaits you here.
The David Allen Company
Speed Keys - for Windows
Finally - a list of all the major Windows shortcut keys...