>I would like a free or cheap program for displaying a folderfull of .jpg images (or maybe other formats) that can display them sequentially as a slideshow or tiled with thumbnails. I would also like it maybe to do some very simple editing, such as rotate, resize, change quality setting, change format, and rename. The program should load and unload quickly, be easy to uninstall, install no spyware, and be otherwise well-behaved.
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>People often use the software that comes with their digital camera for this stuff. But I don't have one and don't intend to buy one real soon. If I did buy one, I could decide that I didn't like the software that came with it.

CHeckout Windows XP. Most of what you want is built-in.