Notepad is a given. Its on every Windows machine, going back to Win16. When you need to edit something in a hurry, on any machine, then it is the obvious tool of choice. And yet with every Windows release, someone decides to change it. Not in a big way, but for changes sake. To keep them in a job or something.
Some time between Win 3.1 and XP the Find key changed. I cannot remember the details, but it took years to adjust especially when I was still using both the old and the new versions. AARG.
When XP came out, the Goto Line feature became disabled seemingly randomly. AAARG. Turns out someone decided to disable it when in word-wrap mode, to make it different from Windows 2000.
And now we have Vista Beta 2. Although the Find key hasn't changed and Goto Line is still broken in the same way, the Save Changes dialog is different. Load a file, make changes, Alt-F4, it asks you if you want to save the changes and you hit Alt-Y or Alt-N for Yes or No. Not any more. AAAARG. The dialog buttons now says Save/Don't Save with the keyboard shortcuts of S and D. Alt Y/N do nothing except Beep. Why on earth did someone do this? The text changes alone require re-localization for the zillions of languages that Windows supports, never mind the pure annoyance of the change. At least Esc is still Cancel.
Maybe it is crazy stuff like this, multiplied by 1000, that can cause an entire operating system to slip?