If you still have Visual Studio 2003, the only way to build 64 bit applications for Windows seems to be the Platform SDK. This, however, is downward compatible with Visual Studio 6. And most of us probably remember what that means: The STL in there is shite. It’s an implementation from back in 1995. A lot of projects simply don’t support it and recommend you use STLport instead.
OMG, should I really have to install that thing again?