As I was reading through some threads over at Neowin.net's Windows Vista Support forum section, I stumbled upon a thread where someone was asking how to disable the Windows Aero interface through the registry. There were several suggestions made, one of which included that the original poster disable the "Desktop Window Manager Session Manager" service completely, which to me seems like a bad solution even though it would achieve what the original poster was trying to tackle.
You don't need to disable the "Desktop Window Manager Session Manager" service to disable Windows Aero and desktop composition. This can be done from the Windows Control Panel itself (by navigating to Control Panel, Appearance and Personalization, and under Personalization click on "Change color scheme" and then selecting "Windows Vista Basic" from the color scheme list), through Advanced system properties (by navigating to Control Panel, System and Maintenance, System, and choosing Advanced system settings from the task pane on the left, clicking the "Settings..." button under Performance, and then finally unchecking "Enable desktop composition" and clicking on the OK button), or last but not least, the registry:
- Click on Start, and in the Start Search field type regedit.exe and then press Enter.
- If User Account Control prompts you for consent, click on continue or provide the appropriate credentials.
- Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\DWM.
- Look for a REG_DWORD value named "Composition". If this key does not exist, create it.
- Double click on the Composition (REG_DWORD) value and change its value to 0.
- Log off and back on for this change to take effect.
If you want to achieve this through the command line or through a command script, the appropriate command is REG ADD HKCU\Software\Microsoft\Windows\DWM /v Composition /d 0 /f.
That will disable desktop composition even if your computer supports it. To re-enable Windows Aero and desktop composition, change the Composition (REG_DWORD) value to 1 or change the scheme by going to Control Panel, Appearance and Personalization, and under Personalization click on "Change color scheme" and then select Windows Aero from the color scheme list.
Alternatively if you would want to re-enable Windows Aero through the command line you can achieve this by running REG ADD HKCU\Software\Microsoft\Windows\DWM /v Composition /d 1 /f.
NOTE: This will NOT, under any circumstances, allow you to enable Windows Aero on graphics cards that do not have the proper support for Windows Aero or do not fit the prerequisites for enabling Windows Aero and desktop composition (for example, GeForce MX 440 graphics cards). For more information on the prerequisites and hardware requirements for Microsoft Windows Vista, please visit the Microsoft Knowledge Base.