avoid file replace

Hello

Is it possible to avoid the overwrite of some existing file on the target directory if it exists ?

Thank for any help

!include "logiclib.nsh"

${Unless} ${FileExists} "c:\somefolder\somefile.txt"

  SetOutPath "c:\somefolder"

  File somefile.txt

${EndUnless}

?

Thank you very much !
I will try that.

BTW I have a lot of problem on Vista because NSIS can create a new folder the Program Files folder but the user do not have the rights to write a config in that folder