Application can be assigned a shortcut key in Windows 7. The application would launch when the combo of keys is pressed which you entered as the Shortcut Key for that application.
To create Shortcut key for any application in Windows 7:
1. Right-click the program icon and select Properties.
2. Select the Shortcut tab
3. Click in Shortcut key textbox
4. Enter the keyboard shortcut for that program
5. Press OK to exit.
6. Use the Keyboard shortcut combo to launch the application..
Like the way i have used a combo of keys Ctrl+Alt+C to launch calculator application other applications can also be launched using Shortcut keys.
"Windows 7 Tips: Assign Keyboard Shortcuts for Programs"
Reference : www.WindowsVJ.com