One other thing you might try is to check your Windows Experience Index. It
has to be above a certain value (I do not remember the value now) to be able
to run Aero. Whenever I install new video drivers for my card I have to
refresh the Windows Experience Index. During the installation of Vista, the
WEI is determined. In my case when I installed Ultimate, the video rating
were 1.0 with the default drivers. After installing Ultimate, the very next
step was to install the latest video drivers. When I looked at the WEI, it
was showing 1.0/1.0 and "Unrated". I "refreshed" the WEI and now had 5.9/5.5
for the two video ratings and now had Aero capabilities