All of the projects in Visual Studio create 32-bit and 64-bit versions except for the shell. The shell only has 32-bit defined as a target. There is no real reason for this except that it would take a few minutes to set it up. The shell works fine in 64-bit, SCons builds it in 64-bit, and you get this weird setting of "Mixed platforms" in the Visual Studio UI because most projects can do 64-bit but the shell can't. I've done this (created a 64-bit VS build of the shell) at least three times on my home machine and it would save additional work to just check it in.