Here is some info regarding the compatibility of different versions of Visual C++ and the kX Project SDK. Visual C++ 6 This is the recommended version as this is the version used to create the SDK. Visual C++ .NET 2002 Changes in the MFC libraries make this version incompatible with the kX SDK. You can however create plugins, etc, using this version, provided that you link with the MFC library files from VC++ 6. (this seems to work, but it is possible that you could run into problems, and you still need to get a hold of the MFC library files from VC++ 6, so if you have these files, then you probably have VC++ 6 and should probably just use it instead) Visual C++ .NET 2003 This has the same issue with the MFC library as the 2002 version, but due to additional incompatibilities it does not seem that this version can be used to create kX Plugins, etc. Addtional Info: Current versions of Visual C++ include a downgrade option. What this means is that you could purchase the current version (i.e. Visual C++ .NET 2003 Standard), and use your downgrade option to get Visual C++ 6, etc for the price of the media plus shipping and handling (i.e. media only version). See the following link for more info: Downgrade Information for Visual C++ I thought this info might be useful to anyone wanting to create kX Plugins, but are not sure what thier options are. Of course this information may not be accurate with future versions of kX, and Microsoft could change it's downgrade options in the future, so be sure to check these things before deciding to purchase anything in order to develop kX plugins, etc.