If Windows is there, and everything else works ok, You wouldn't really need
to do a complete reinstall... only fix the problem that is causing windows
to not boot. This could either be a grub problem or an issue with windows
boot files. Reinstalling/fixing grub would take care of the former, and
running system repair disk for windows would take care of the later. There
is a nice tuturial somewhere on how to get grub2 fixed to see windows if
that is the problem. Maybe someone remembers where that is at.