Sorry for the double post, but:
LOOK WHAT I'VE FOUND:
ENABLE VISTA IN INTEL GMA 950 GRAPHICS CARDS:
Look if that works for you. Maybe it works with GMA 900.
BTW, bad luck for me.
So I finally installed my new Graphics Card, but it was an ATI Radeon 9250 instead of a 9800... i also added +512MB RAM so i have 1GB RAM now (needed for Aero).
The controller is XDDM! (Xp Device Driver Model) No WDDM controller for me... sh*t!
If someone knows about a Vista controller for this card or a tweak, plz let me know.
BTW, Nylock's tweak it's only for beta and RC versions. Not working on RTM.