[MDinc]

тогда уж так

The DeleteRegKey problem is probably a windows bug and not nsis, either way, using SetRegView 64 on 32 bit systems is not supported

To detect x64, include x64.nsh

${If} ${RunningX64}
MessageBox MB_OK "running on x64"
${EndIf}

edit: gah too slow, kichik beat me to it