Engadget has a graph showing some crash statistics for Vista. I have no idea whether this data is good, bad or indifferent, but it’s interesting for what it is.
I personally don’t find that Vista crashes all that much, although I have run into problems in the past with what I thought was a Flash/browser problem and the driver from WebcamMax. Other than that the sleep/hibernate issues have been a pain on my Toshiba M700 Tablet PC.
All this being said, is Vista worse than XP? Absolutely not. I can see why people go with XP for older hardware, however, Vista is quite comfortable to use. In fact, as long as there are drivers for the hardware, I’ve started recommending it for friends and family.