The latest DirectX comes with two versions of managed DirectX the old 1.1 version and a 2.0 beta (which doesn't seem to play nice with 2.0RTM)

If, when you add the DirectX references, you avoid adding the v2.0 Microsoft.DirectX library and instead only add the older versions (marked v1.1.4322) then everything seems to work okay.

There do seem to have been a few breaking changes between versions though so if the code was written against the 2.0 beta you might have to amend it slighty or use the beta 2.0 runtime (at least until a new DirectX SDK comes out, which will hopefully not be too long!)