It would be great if Win Toolkit could perform Driver compatability check during drivers integration. So that no x64 drivers would integrate into x86 distro.

WinToolKit does that.  The exception is that if a driver specifies files for *both* x86 and x64 versions, then those files are included.

but sometimes i can see only Nt5.0 drivers in the list. they are incompatable!

You see them in the list of integrated drivers, or what?  Please explain exactly what you did where you saw this problem, preferably with links to the drivers, screenshots showing what you did and the results, and any Win Toolkit logs that were produced.

 

Cheers and Regards