If you have access to VS2005 then you don't have a problem. You can also get complete free tools from Microsoft which will build for WM2003 and run on the X51.
You really need to be on one of the dev forums like pocketmatrix (
www.pocketmatrix.com) to get full info.
C++ is the language of choice for games developers with C# getting a look in for applications. VB is of course used by lots of application developers.