If the hardware requirements are met.. then..
according to F1
My computer meets the minimum recommendations, but I’m still not getting Windows Aero. Is there anything else I can do?
Yes. Make sure that the color is set to 32 bit, the monitor refresh rate is higher than 10 hertz, the theme is set to Windows Vista, the color scheme is set to Windows Aero, and window frame transparency is on.
To set the color to 32 bit
Click to open Display Settings.
Under Colors, select Highest (32 bit), and then click OK. (If you can’t select 32 bit, check that your resolution is as high as possible, and then try again.)
To set the monitor refresh rate
Click to open Display Settings.
Click Advanced Settings.
Click the Monitor tab, and then click a refresh rate that’s higher than 10 hertz. The monitor will take a moment to adjust. If you want to keep the changes, click Apply. If you don’t apply the changes within fifteen seconds, the refresh rate will revert back to your original setting.
Note
Changes to the refresh rate affect all users who log on to the computer.
To change the desktop theme to Windows Vista
open Theme Settings.
In the Theme list, select Windows Vista , and then click OK.
To change the color scheme to Windows Aero
*open Appearance Settings. *
In the Color scheme list, select Windows Aero, and then click OK.
To turn on window frame transparency, the color scheme must first be set to Windows Aero.
Click the Start button , click Control Panel, click Appearance and Personalization, click Personalization, and then click Window Color and Appearance.
Select the Enable transparency check box so that it is checked.
Note
If you see the Appearance Settings dialog box instead of the Window Color and Appearance window, the theme might not be set to Windows Vista, the color scheme might not be set to Windows Aero, or the computer might not meet the minimum hardware requirements for running Windows Aero.
That’s it..
P.S : But it will still show ‘Windows Vista’ or ‘Modified theme’ in the theme window.