How can I transfer user profiles from Vista x64 to Windows 7 x86?
If I try to start the migwiz from Windows 7 x86 on the Vista x64 machine, it complains about the wrong architecture.
Your risk here is that the architecture is different, and therefore if you had 64-bit DLLs and executables migrated over, they won't work, and instead of fielding calls of "the stupid thing doesn't work", Microsoft won't support it in the first place.
I don't think it's possible through any conventional methods. Why are you migrating to 32-bit Windows 7 anyway? What is stopping you from going to 64-bit?