There were several things that made Vista a problem for people, including:
  • Expectation of running a 2007 OS on 2001 hardware.
  • Manufacturers slow to produce device drivers.
  • Software vendors taking their time to catch up with Vista's new enforcement of development rules in existance since the 1990s.
  • Some real flaws, some of which were fixed by SP1 and a few more fixed by SP2.

You can run into this even today with new hardware though. I have an Intel D2700MUD board that had no decent video drivers until about June of this year, and even the ones on their download site now don't install correctly (Windows shows a broken video device in DevManager and "missing or corrupt driver" as the reason).

Companies like Intel are getting really bad. They can't even get the specs list right on their own products. See D2700MUD where the photo clearly shows the 4 back panel USB ports despite the specs there saying there are only two!