[gora]

почему-то съедается скобка в пути у Programm Files (x86 »

Попробуйте так:

Код:

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

CLS
COLOR 1A
Set xOS=x86
If Defined PROCESSOR_ARCHITEW6432 (Set xOS=x64) Else If "%PROCESSOR_ARCHITECTURE%"=="AMD64" Set xOS=x64

SET FileName=%FileNameX86%
SET PFPath=%PROGRAMFILES(x86)%

IF %xOS%==x64 (
    IF DEFINED FileNameX64 (
        SET FileName=%FileNameX64%
        SET PFPath=%PROGRAMFILES%
    )
) ELSE (
    SET FileName=%FileNameX86%
    SET PFPath=%PROGRAMFILES%
)

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