Here's my experience - figures rounded off.

In my company there's 140 computers. 90 XP with Office 2003/2000, 30 Vista with office 2007. Rest are Unix/BSD/Linux/2003 Servers.

Of the 30 Vista, 15 users have requested going back to XP. 10 of these users can't be bothered to learn anything new and like the XP (which they've used a long time now despite the fact we've "gone back to classic view"). The other 5 are more technical, 1 is an accountant who likes to dabble in Excel VBA, he's threatened to resign if he doesn't get XP and Office 2003 because the security stuff and everything new is doing his head in! The others have various (and genuine) issues regarding the existing special applications we use.

We're not a big company and having to learn something new is a huge strain on resources. Vista is just too much stress and strain to support compared to XP. One chap had to spend over 20 hours trying to find an answer to a Vista/office 2007 configuration fault.

Nope, it's too revolutionary for the average user and support. We'll get there eventually, but we don't have the training support many other companies do. If a car manufacturer decided to shift pedal controls in cars after a few years what do you think would happen?