PCs from Hewlett-Packard, Gateway, Lenovo, and other major computer makers that contain a widely used Intel chipset can't be upgraded to Windows Vista Service Pack 1 if they're running certain drivers.
Microsoft has said that Vista SP1 won't work with "a small number of device drivers." The list, however, includes drivers for an Intel chipset that's found in thousands of PCs and laptops.
A service pack that was supposed to fix some of the problems with Vista is actually causing more problems than it fixes. Not a brilliant move by Microsoft.
I know the IT department for my employer has already declared that Vista will not be deployed on any of the corporate computers. There's only one exception to that rule: one of our engineering computers has Vista installed which allows us to test a companion PC application for some of our instruments. That one computer is a standalone machine, not connected to our network.