Thanks for the link, but this isn't what I'm looking for. I don't need any image viewer.
When opening a file in an application and selecting a folder with images, a thumbnail picture is displayed alongside the filename so that a ready indication is available as to what the picture contains without having to open the picture. This is i.a. available for jpg, also for bmp and png, but not for psd (Photoshop).
I am using Windows XP SP3.