[Coda]

Photoshop Elements is a piece of crap if you want to do anything more than just touch up actual photographs. If that's what you want, it's a good tool for the job and it's my father's software of choice. The moment you want to go beyond that, its limitations start getting in the way FAST -- it is NOT a scaled-down version of Photoshop and it doesn't offer most of the functions Photoshop offers. And if you don't need the power of Photoshop Elements, there are other tools that don't cost anything that can do simple things like cropping and level adjustments. (Actually, I think Windows's built-in image viewer can do that.)

InDesign is probably not what you want. It's a professional desktop publishing tool, for taking your printed materials to the next level in terms of layout and polish. You would use a tool like InDesign if you were hired to take the documentation written by the tech writer and turn it into a paperback manual or a CD case insert. Specifically: It's not a word processor and you'll get very annoyed by it if you try to use it as one. If you're looking for free software equivalents, Scribus fills that niche; it's pretty powerful and has good quality output but it's even harder to use than InDesign.

Inkscape rocks. It's like Illustrator, and it's one of the best open-source programs I've ever used -- and this is saying something because I was a heavy Linux user for a long time. That said, it's actually not the ideal tool for creating diagrams because it's intended for creating artwork. It can do the job and do it well, but other tools exist specifically designed for that job: Microsoft has a program called Visio, and there's an open-source imitator called Dia. Dia's not particularly user-friendly, though, so on a budget you might try both Dia and Inkscape and see which you're more comfortable with. (Inkscape will produce better results in the long run but you'll work harder to get those results. Visio's pretty good.)