1. On your desktop right click on the shortcut of your favorite app.
2. Click on properties.
3. You should see "shortcut key:" in the dialog box.
4. Chose your hotkey on your keyboard.
5. Hit OK. And you are done.
Here are some recommend keys for the hotkeys: F1, F12, F6,F7 (Function description of F keys »wiki.answers.com/Q/What_are_the_ ··· keyboard
Also you can pick any other key on your keyboard.