With 64-bit applications taking the 3D world by storm, Blender is no exception. Adkiller, who brought us the first x64 Windows build of Blender 2.41, has posted his latest Blender 2.41 and YafRay 0.0.8 x64 builds which fixes some Blender 32-bit compatibility issues.
From the thread:
The applications were built with SSE3 optimizations but is also useable on SSE2 CPUs. Please post in this thread if you have any problems. I have made some code tweaks to utilise 64-bit optimizations. You should be able to see a 40%-60% speed increase in most cases. Since this is a native x64 application, it takes advantage of 64-bit OpenGL drivers. We have thoroughly tested the above builds and it is stable as the official 32-bit releases.
Before using these builds, please be advised that issues concerning the compatability between the 32-bit and 64-bit Blender files may exist. If any issues are found, please post them on the Blender thread.