Tutorial:
Step 1
Install WinUAE

if you don’t haven’t done yet

Create your favorite WinUAE configuration choosing the System (i.e. Amiga 500, Amiga 1200 and so on…), the hardware, video and audio settings of choice.
Save your configuration in your WinUAE configurations folder.
Step 2
Open Notepad.exe
Paste the folling line of text into the notepad:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\adf_auto_file]
@=""
[HKEY_CLASSES_ROOT\adf_auto_file\shell]
[HKEY_CLASSES_ROOT\adf_auto_file\shell\open]
[HKEY_CLASSES_ROOT\adf_auto_file\shell\open\command]
@="\"C:\\Programmi\\WinUAE\\WinUAE.exe\" -f \"C:\\Programmi\\WinUAE\\Configurations\\A500.uae\" -0 \"%1\" -s use_gui=no"
Note: the “c” is your system folder. The “C:\\Programmi\\WinUAE\\WinUAE.exe\” and the "C:\\Programmi\\WinUAE\\Configurations\\A500.uae\” are the path relative to your WinUAE installation and the default WinUAE config file. Edit the path if necessary.
Save the file as “adf_auto_file.reg” (without quotation mark) to your Desktop or to whatever folder you want.
Create a new empty txt file with notepad and paste the following lines of text:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.adf]
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.adf\OpenWithList]
"a"="\"C:\\Programmi\\WinUAE\\WinUAE.exe\" -f \"C:\\Programmi\\WinUAE\\Configurations\\A500.uae\" -0 \"%1\" -s use_gui=no"
"MRUList"="ba"
"b"="winuae.exe"
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.adf\OpenWithProgids]
"adf_auto_file"=hex(0):
Note: the “c” is your system folder. The “C:\\Programmi\\WinUAE\\WinUAE.exe\” and the "C:\\Programmi\\WinUAE\\Configurations\\A500.uae\” are the path relative to your WinUAE installation and your default WinUAE config. Edit the path if necessary.
Save the file as “DotAdf.reg” (without quotation mark) to your Desktop or to whatever folder you want.
Create a third text file with notepad and paste into it the following line of text:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf]
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell]
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit]
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit\Command]
@="\"%SystemRoot%\\system32\\NOTEPAD.EXE\" \"%1\""
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit.WinUAEA1200FS]
@="WinUAE A1200 Full Screen"
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit.WinUAEA1200FS\Command]
@="\"C:\\Programmi\\WinUAE\\WinUAE.exe\" -f \"C:\\Programmi\\WinUAE\\Configurations\\A1200FS.uae\" -0 \"%1\" -s use_gui=no"
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit.WinUAEA500]
@="WinUAE A500"
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit.WinUAEA500\Command]
@="\"C:\\Programmi\\WinUAE\\WinUAE.exe\" -f \"C:\\Programmi\\WinUAE\\Configurations\\A500.uae\" -0 \"%1\" -s use_gui=no"
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit.WinUAEA500FS]
@="WinUAE A500 Full Screen"
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Edit.WinUAEA500FS\Command]
@="\"C:\\Programmi\\WinUAE\\WinUAE.exe\" -f \"C:\\Programmi\\WinUAE\\Configurations\\A500FS.uae\" -0 \"%1\" -s use_gui=no"
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Open]
[HKEY_CLASSES_ROOT\SystemFileAssociations\.adf\Shell\Open\Command]
@="\"%SystemRoot%\\system32\\NOTEPAD.EXE\" \"%1\""
Note: the “c” is your system folder. The “C:\\Programmi\\WinUAE\\WinUAE.exe\”. The other path are related to every eventual configurations you made via WinUAE (i have 3 configurations in this example: Amiga 1200 Full Screen, Amiga 500 and Amiga 500 Full Screen.
You can create your own configurations and edit the path of this third reg file.
Save the file as “SystemFileAssociations_adf.reg” (without quotation mark) to your Desktop or to whatever folder you want.
Step 3
Use an administrator account and run the previously created .reg file (double click on it) to insert those entries into the Windows Registry. If the system request the to continue, give the appropriate permission to operate, by replying “continue”.
Step 4: PlayTime

Double Click on any amiga ADF to run it. Right Click on the ADF to run it with the appropriate configuration you have previously created.
Note: if you have Windows 7 64 bit, path and configurations may change due to different registry path (x86 or x64).
I will try to find the reg files and post the reg files here directly.