Seriously this is the easiest thing to do actually.
Download psicon.dll
From :
psicon.dll download - free dll files
Place it in c:\program files\common files\adobe\shell
If the shell directory isn't there create it.
now open notepad and copy and paste the next few lines:
Code:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SharedDLLs]
"C:\\Program Files\\Common Files\\Adobe\\Shell\\psicon.dll"=dword:00000001
[HKEY_CLASSES_ROOT\.psd\ShellEx]
[HKEY_CLASSES_ROOT\.psd\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{0B6DC6EE-C4FD-11d1-819A-00C04FB69B4D}"
[HKEY_CLASSES_ROOT\CLSID\{0B6DC6EE-C4FD-11d1-819A-00C04FB69B4D}]
@="Photoshop Icon Handler"
[HKEY_CLASSES_ROOT\CLSID\{0B6DC6EE-C4FD-11d1-819A-00C04FB69B4D}\InProcServer32]
@="C:\\Program Files\\Common Files\\Adobe\\Shell\\psicon.dll"
"ThreadingModel"="Apartment" Save the file as psdreg.reg
Now double click the file and then click yes. Now just either restart or kill and restart the "explorer.exe" process.
go look at any .psd and you will see thumbnail ;-)