[Blind-sysadmins] accessible windows pre-execution environment

Hello, I'm trying to clean off a laptop that has been infected with a trojan. It's an xp machine, and the trojan has replaced the lsass.exe program along with another .dll file in the windows\system32 directory. I was wondering if anyone had either an accessible copy of WinPE or BartPE environment or a way i could make it work with speech? Or, any other alternatives, a reinstall is not an option for this situation. Thanks. Dave.