Guidelines regarding categorization.
Ideally, everything should be categorized. Try to find an existing category that fits before creating a new one.
Note that having separate categories for images is not the ideal. It leads to parallel, redundant categorization, which is more maintenance. It's better to put the picture of "the thing" in the same categories as the article of "the thing", so that you get a nice gallery on the same page as the article listings. But in the case of computers, which we categorize a dozen different ways, that becomes tedious as well. So instead, put the images in an ancestor category.