[gora]

Тогда так:

Код:

@ECHO OFF
SET ProgName=WinRar
SET ProgVer=4.20 Beta 3
SET FileNameX86=wrar420b3ru.exe
SET FileNameX64=winrar-x64-420b3ru.exe
TITLE %ProgName% %ProgVer%

CLS
COLOR 1A

Call :_Set_Var

ECHO xOS=%xOS%
ECHO PFPath=%PFPath%
ECHO FileName=%FileName%
Pause

:_Set_Var
Set xOS=x86
If Defined PROCESSOR_ARCHITEW6432 (Set xOS=x64) Else If "%PROCESSOR_ARCHITECTURE%"=="AMD64" Set xOS=x64
SET FileName=%FileNameX86%
SET PFPath=%PROGRAMFILES%
IF %xOS%==x86 GoTo :EOF
SET PFPath=%PROGRAMFILES(x86)%
IF Not DEFINED FileNameX64 GoTo :EOF
SET FileName=%FileNameX64%
SET PFPath=%ProgramW6432%
GoTo :EOF

Так не должно зависеть от среды запуска (х86\х64) на х64 ОС