re-install of vista

my laptop for the past week keeps freezin constantly now, and is becoming extremely irritating, it mainly freezes though when it is bootin up, at the point where its loading vista, just before you sign in, what i wanted to kno, is there a way of reinstallin jus the windows files through the recovery thing, or would i have to wipe the computer clean to do so

if someone could tell me how to do this or provide a link i would be extremely grateful

for some reason the recovery thing never works for me