(via Gruber — I swear we have separate sites, really)
The plain fact is users will not read anything you put on the screen.
This is one of the many reasons why Windows 7 is so mediocre. The interface is smothered with explanatory text. (Was Vista as bad in that regard? I never used it.)
Microsoft’s typical response to bad designs is to add text to explain them. Then, when that doesn’t work, add a text-heavy dialog box to ensure that the user noticed the other text. (I will never stop laughing at that dialog.)