[Richard]

It's fairly new but for those techie folks out there I found this:

Managed DirectX is the new core technology added to the DirectX API. It requires both Visual Studio .NET and the .NET framework for development. By eliminating the COM interop layer it enhances performance over previous typelibs. For example, the performance goal for Managed Direct3D is 98% of core C++ performance. By using managed code, there is a minimum reduction in code of 10% and upwards of 40% in some cases. Managed code is a great productivity improvement and frees developers from having to deal with memory management tasks. It enables Visual Studio .NET developers to have easy access to the DirectX APIs through managed code. They can now take advantage of the multimedia functionality and hardware acceleration of DirectX. The following are the main features of Managed DirectX

Full support for all of the features in Direct3D, D3DX, DirectDraw, DirectPlay, DirectInput, and DirectSound.
Support for simple playback of many common audio and video formats.
A near 1 for 1 complement of samples when compared with C++.
Code reduction: Most common tasks done in DirectX are done with fewer lines of code via Managed Code.
Tight integration with .NET - Managed DirectX fully utilizes .NET and it's common types anywhere it can.
A Managed DirectX Application Wizard