For you vista users who don't have a good enough graphics cards
Using a couple of test systems, I found a technique to sometimes force Windows Aero UI on PC's, note that this won't work on 100% of the systems running Vista, but it does work.
Running Windows Vista (you need not to be Premium-Ready)
WDDM-complaint Video Card
In the Registry Editor (Start, Run, type regedit, and click OK), navigate to the following key:
Add a new subkey named DWM and then create a DWORD setting named EnableMachineCheck. Leave the value of this setting at 0, which disables Vista’s DWM-related hardware checking
* It does not work on all systems.
* Even if it does work, it can make your system run extremely slowly. (There’s probably a reason Windows shut off Aero Glass.)
* A blue-screen of death (BSOD) is evident, but that may take a couple of hours from showing up.