I also installed the just released beta 1 of the ATI drivers for Windows Vista to get the best possible graphics experience. The Aero Glass theme runs without problems on my ATI RADEON 9800 PRO video card with 128 MB of memory. Unfortunately I am missing sound as there are no drivers for the Soundblaster Audigy as of yet.
So now I could finally try out Adam Nathan's Avalon Cards Sample after compiling it. You can see it in the following screen shot. Notice the translucency of the non-client areas of the windows with the Aero Glass theme.
I can't notice if it runs any smoother than it did with the WinFX Beta 1 RC1 on Windows XP on my machine. Moving the mouse over the cards still produces a high CPU usage (up to 80%), so it seems not all work is offloaded to the GPU.