First, what is your Windows Experience Index for graphics? The graphics
portion has to be above a minimum in order for Aero to be available, I forget
what the minimum is, maybe 2 or 2.5?
If you installed Vista yourself, during the installation process it ran the
Windows Experience Index automatically for the first time. If a new machine
with Vista pre-installed, it might be that WEI has not been ran yet due to
the way manufacturer installed Vista.
When I have installed a different video card and the drivers for it, the
graphics portion drops back to 1.0 and I do not have Aero available. I have
to "re-fresh" or "Update my score" for it to pick up the new card and
drivers. Example, I recently changed to ATI HD2600XT video card. After adding
card and new drivers, no Aero - the graphics portion of WEI was 1.0/1.0.
Refreshed score and Aero was back and graphics score was 5.9/5.5. Before this
card, I had X1650 card and everytime I would update drivers, I would loose
Aero and score would drop back to 1.0/1.0 until I refreshed score, then
everything would be ok. Apparently when a new card or new video drivers are
added, the WEI is not automatically updated, instead it defaults back to
1.0/1.0 for the graphics. I have Vista Ultimate on two machines and have to
do this when updating video drivers or changing cards.
Now after long story above, check your WEI and see what video portion is and
also do a refresh/update of the score/index. If not familar with WEI, post
back for more help.