i found on a old post a way to use %systemdrive% on a setup.iss answer file it uses a batch like this: parse.bat @echo off echo Starting... echo . echo Wait... echo . echo Wait type %systemdrive%\Photoshop\setup.txt|%windir%\sed.exe 's/\%%systemdrive\%%/%systemdrive%/g'>%systemdrive%\Photoshop\setup.iss what you have to do is put szDir=%systemdrive%\Archivos de programa\Adobe\Photoshop CS in your setup.ss, and then rename it to setup.txt also, you need to put the sed.exe file in the windows directory sed.exe it works perfect for me with photoshop, dreamweaver, and flash i use it like this in my RunOnceEx.cmd : REG ADD %KEY%\032 /VE /D "Adobe Photoshop CS" /f REG ADD %KEY%\032 /V 1 /D "%CDROM%\software\Photoshop\Photoshop.exe" /f REG ADD %KEY%\032 /V 2 /D "%CDROM%\software\Photoshop\parse.bat" /f REG ADD %KEY%\032 /V 3 /D "%systemdrive%\Photoshop\setup.exe -s" /f i made a sfx for the photoshop folder, it decompress to the HD, run the .bat, then run setup.exe -s, and at the end with my cleanup.cmd erase the photoshop folder its better explained here, but its in french Laboratoire des Technologies Microsoft - Supinfo Paris maybe this is what your looking for?