Since today, nivenCore works properly on x64, just tested, the
unit-tests ran fine (tested on Windows Vista x64). Took me a while to
recompile boost-1.33.1 for x64 (using the
vc-8_0-amd64) toolset, but
it was worth it :) Python 2.5 works, too, there is even a native x64
release on their page.
[Update] Added screenshot: