Adding Open With to the Right Click in the Explorer

To add the option Open With when you right click on a file in the Explorer:

1. Start Regedit
2. Go to HKEY_LOCAL_MACHINE \ Software \ CLASSES \* \ shell \ openas \ command
3. If this key isn't there then just create it
4. Give it the value of C:\WINDOWS\rundll32.exe shell32.dll,OpenAs_RunDLL %1