The GeForce2 MX400 is an older NVIDIA graphics card which is no longer supported in Windows Vista or later versions of Windows (including Windows 7).
Windows Vista introduced a new display driver model (WDDM) which offers significant changes and improvements over the previous model (XPDM) used in Windows XP/2000/2003. WDDM requires advanced GPU features which are not available on many older graphics cards. Windows Vista can use XPDM drivers which means you can install versions of drivers which vendors have provided for Windows XP, but there are a lot of stability issues with most of them. Vista includes updated XPDM drivers for a limited number of legacy cards which are installed automatically work properly. For most legacy display adapters it will simply install the “Standard VGA Adapter” driver. This driver works fine for many things, but it ignores the extra features supported by many adapters (like multiple displays, larger screen resolutions, configurable CRT monitor refresh rate, and DirectX/OpenGL hardware acceleration).
The GeForce2 MX400 has decent enough features to be useful for regular users who don’t need a lot of GPU power (for gaming etc.). The problem is that the XPDM drivers for legacy NVIDIA display adapters included with Windows Vista only support the GeForce4 series or newer. The GeForce2 MX400 is installed as a standard VGA adapter which cripples many of it’s capabilities.
Luckily, the Windows 2000/XP drivers provided by NVIDIA (version 91.31) work flawlessly in Windows Vista and Windows 7 without any modifications. Download the driver package here. The installation will fail if you try and run it, but you can extract the contents of the exe package to a directory using WinRAR. Open Device Manager (devmgmt.msc) and expand the “Display Adapters” section, then update the driver for the “Standard VGA Adapter” (right click on it and select “Update Driver Software…”). Choose to manually select the device driver and then browse to the location where you extracted the NVIDIA driver files (you should see the ‘nv4_disp.inf’ file within the directory). Windows should find the correctly matching “NVIDIA GeForce2 MX/MX 400” driver and allow you to install it. Once you reboot the system the driver should work properly and support all of the adapter’s additional features. You can confirm that they are working correctly by running ‘dxdiag’ and checking under the ‘Display’ tab. All of the features listed under the “DirectX Features” section should be “Enabled”.