As to the bit about composing diagrams in notepad or a linux text editor, it's my understanding that most text editors (Open Office and MS Office I know from personal experience) have at least one fixed-length font, sometimes several, and you can always install one.
It'll be the computer that does/does not have fixed-width fonts. (And, really, I doubt any computer doesn't.) Both Offices (and most other software) will work with what's installed if there aren't any irregularities. But using a word processor to edit text might be asking for trouble if you don't know what you're doing. (Creating a batch file or raw HTML in Word[1], frexample, really only gives you what you want if you mess with a number of options in the save dialogue.) I wouldn't class Word and OO's Writer component "Text editors", in general.
I also find it quite easy to hit (say) the "Windows-R" combination and type "notepad<enter>". It's as easy as using "winword<enter>" (assuming that's installed, and not outside of the %PATH%/equivalent), without the aforementioned hassle, and far easier than finding the locally installed Word Processor in the start menu. But then I'm a bit geeky, in that respect, and rarely use the mouse where I don't need to, and will put the i-tag around
italics by keyboard rather than abandon it with one hand to move the mouse to (optionaly) select text and then click the form button I can see above..
Sorry, that's my last off-topic.
Ditto! (Well, I hope.)
[1] Don't talk to me about saving a formatted document as HTML. Messy, messy markup always results. Sorry, my geekiness continues to shine out, I'm sure, but <DIV>s should be used sparingly and intelligently, not with repetitively similar styles for every paragraph, or <SPAN>s at each and every point where minor changes occur, never mind the overuse of "position: absolute"... Right, I'm done moaning. We now return you to you regular programme. Or "program", if you prefer.
(Edited: because the oen disadvantage of typing tags, instead of using the mouse to select and modify sections of text, is that you can accidentally put a close tag instead of an open one!)