Just read an interesting analysis at http://firingsquad.com/hardware/windows_vista_aero_glass_performance/ where they tested a couple of different systems running Windows Vista with Aero Glass switched on and off. (Windows Aero - if you're not aware of it by name - is the new user interface functionality, with transparent windows and the swish new effects present all through Vista)
The cynic in most techies would assume that flashy graphics mean hammering the system performance; I've known plenty of people who even switched off all the fancy UI features, on the basis that the machine would be a few % more responsive... remember the old advice on Windows 3.1 or 95 to not use a graphical desktop backdrop since that put an overhead on system performance?
Anyway, the FiringSquad results are predictably games-focused, but draw an interesting conclusion - graphical performance is, in some cases, marginally better with Aero switched on, and even in the cases where it isn't, it's only fractionally less so.
"Quite frankly, we were shocked by these results."
So, the moral of the story is... switch on all the bells and whistles if you can 🙂