Bug 352510 - Unsupported windows versions need error message when attempting to install (string checkin). r=sspitzer, a1.9blocking=vlad

browser/locales/en-US/installer/custom.properties

@@ -72,6 +72,7 @@ ICONS_STARTMENU=In my &Start Menu Programs folder
 ICONS_QUICKLAUNCH=In my &Quick Launch bar
 WARN_WRITE_ACCESS=You don't have access to write to the installation directory.\n\nClick OK to select a different directory.
 WARN_DISK_SPACE=You don't have sufficient disk space to install to this location.\n\nClick OK to select a different location.
+WARN_UNSUPPORTED_MSG=Sorry, ${BrandShortName} can't be installed. This version of ${BrandShortName} requires ${MinUnsupportedVer} or newer.
 
 STATUS_INSTALL_APP=Installing ${BrandShortName}...
 STATUS_INSTALL_LANG=Installing Language Files (${AB_CD})...