NT Server reinstall

I have taken over a very overused and corrupt NT Server. I do not want to lose any current files and do not have the time at this point to reformatat and reinstall from backup. I know I can take the PDC offline (we do not have a BDC, go figure) and install NT into a new directory but I’m not exactly sure how this would work. What happens to the original install and do I delete the original WINNT folder?