I run into this report by Pfeiffer Consulting on Windows Vista vs. XP and Mac OS X that among other things mention mouse precision. Something that every CAD user knows how important it is.
As far as Windows Vista was concerned, it was important to conduct the necessary benchmarks to compare the new release with currently installed versions of Windows. In the light of the results, the core recommendation coming out of this research is simple: before deciding on an upgrade to Windows Vista, it seems wise to conduct thorough productivity analysis in a concrete workflow situation to see if User Interface Friction here would negatively impact overall efficiency. This is particularly true in creative industries such as design, publishing and photo retouching, where mouse precision is a major concern. Overall, Mac OS X remains the most fluid environment of the three systems tested.
Mouse precision is obviously essential for any task where precise positioning of the cursor is essential> this is the case in graphic design, CAD, retouching, page layout and web design, among others.
The result below is according to the test report not hardware related.
I've not been using Mac OS X but I don't feel there is any difference between Vista and XP when it comes to the mouse.