If your Vista's GUI changed to Basic and doesn't want to go back to Aero, then use my tutorial.
This helped many of my friends who were annoyed by this. But this tutorial will work probably only when Vista says 'your graphics interface has been changed to vista basic' or something like that.
Ok now, try this trick.
1. Click Start, type regedit.exe in search field
Registry Editor (Regedit) will open
You have to ensure that these registy entries exist:
HKCU\Software\Microsoft\Windows\DWM\Composition set to 1 (32-bit DWORD)b.
HKCU\Software\Microsoft\Windows\DWM\CompositionPolicy set to 2 (32-bit DWORD)
Note: if they don't exist, you'll have to create them.
2. Restart the Desktop Window Manager Session Manager service:
Click Start and type cmd.exe in search field
Command Prompt will open
Type these lines pressing ENTER after typing each line
a. net stop uxsms
b. net start uxsms
That's it. Your Aero interface should work now.
Wish you good luck and have fun with Aero :)