批处理求助！！！？！！！！！！

@echo off
color 2F
echo ---------------------------------------------------------------------------
echo.
echo     即将进行全新安装:Windows XP......
echo.     
echo ---------------------------------------------------------------------------
echo.
SET /P ST=   请输入 Y (继续安装)或 N (退出安装)：
echo.
if /I "%ST%"=="Y" goto ST
if /I "%ST%"=="N" goto EX
goto EX

:ST
cls
echo ---------------------------------------------------------------------------
echo.
echo      即将进行全新安装:Windows XP ......
echo.
echo ---------------------------------------------------------------------------
SET /P drive_letter=   请输入你要选择安装的分区(C/D/E/F...)
echo.
if /I "%drive_letter%"=="" goto ST
if /I not "%drive_letter%"=="" goto IN
:IN
.\i386\winnt32 /dudisable /s:.\i386  /unattend:.\i386\winnt.sif /makelocalsource /tempdrive:%drive_letter%
echo ---------------------------------------------------------------------------
echo.       
echo         停止安装 Windows XP ......
echo.
echo ---------------------------------------------------------------------------
pause



这个是在硬盘安装的。怎么修改安装的时候先格式化c盘，现在不格式化C盘机会成双系统