...nightmare?
You wanna talk nightmares? Vista. It doesn't get any more nightmarish than that.
The fact that you can say with a straight face that Vista is BETTER than Windows 7 just proves that you have absolutely zero first-hand experience with 7. You probably got stuck with Vista because it came pre-loaded on a machine you bought, and you were too clueless to downgrade to XP, and equally clueless to upgrade to 7 when it came out.
Windows 7 is head over heels, light years better than Vista in every way. Stability, reliability, compatibility, performance, etc etc etc. There is absolutely not one thing Vista does better when compared to Windows 7.
So if you have "clients" who are complaining about Windows 7, it's a very safe bet that these are the types of people who should be using Apple products for all their computing needs, because they're not qualified to eat breakfast without a helmet.
