Why can't PSD thumbnails be displayed in Windows 7?

Using the http://www.codeproject.com/KB/vista/PhotoshopPreviewHandler.aspx solution, thumbnails do work in the 32-bit version of Vista and Windows 7. The preview pane works in the 32-bit and 64-bit. The fact that it isn't a codec has nothing to do with the question on this forum. I would much rather use an open source solution than some proprietary codec.  Are you just another spammer for Axel's paid product? Why do you care if there is a FREE version that does exactly what the forum thread is asking -- displaying thumbnails of PSDs? For the majority of people, who are using 32-bit versions of windows, I'm sure they'd appreciate knowing there is an opensource and free solution. And those on 64-bit, I'd rather have only the partial solution than pay for something that should be free anyway.

That said, the simplest solution was from the Microsoft Support Moderator above -- again for 32-bit installations.

1. Search+Download psicon.dll
2. Place the DLL in C:\Program Files\Common Files\Adobe\Shell\
3. Thumbnail previews of PSD files are now back

You should read this whole tread again: the psicon.dll hack is only a partial solution. Thumbnails are indeed enabled but previews don’t work at all, double-clicking a .psd opens the full Photoshop (provided that it’s actually installed) and psicon.dll does not do anything for x64 systems. 

The Windows 7 shell is able to display and search on metadata but this data is not exposed by psicon, which was written in 2002(!) far before Windows 7 was even designed. Finally, you forgot to explain how to register the dll: simply copying psicon.dll somewhere is not going to do anything so your “simplest solution” is going to be a failure for most users. 

Downloading PSDCodec.dll which is originally part of Microsoft Expression certainly violates Microsoft intellectual property rights, not mentioning that, like psicon.dll, the file has to come from unofficial places (to say the least) and does not work on x64. 

Last, your seemingly favorite solution from CodeProject involves registering assemblies and adding them to the GAC, and comes with batch files containing hard-coded paths to utilities shipping with Microsoft Visual Studio, as they were installed on the developer’s machine – pretty much typical “It works here!” open-source attitude. Are you suggesting that regular users download and install 2GB of Microsoft Visual Studio and Windows SDK, then learn .NET programming to be able to register those files? Besides that I just tried them and all I got was totally blank icons, which comes to no surprise: the author did not implement anything related to thumbnails in his project, it's a preview handler (but suddenly I'm not sure you understand the difference?) and it only works for some  PSDs (try a layered file without MaxCompat).

Now, would you please stop wasting people's time with your non-solutions and move along? It seems that you registered to this forum 5 days ago just to post to this thread but, sorry mate, YOU ARE NOT HELPING.

Come up with something that actually works as Microsoft intended it when they came up with Vista and Windows 7 extensibility points (thumbnails, previews, full-size view in Photo Viewer, slideshows, desktop search, Media Center...), and which does not involves untested, hobbyist, half baked stuff cut’n’pasted from MSDN samples, nor stealing Microsoft or Adobe intellectual property and loading executable files found on random internet sites.

Or perhaps you should just be happy that there exists two professionally supported solutions (David's and mine) that actually work: is not choice a great thing?!