XP reinstall help needed

[Nasa-Tech]

Boot to the CD and chose repair.
>-----Original Message-----
>My computer won't let me reinstall windows xp over
>itself.. here is why.... I can't extract or install
>any .exe or updates I download, so I was told to
>reinstall XP.. but since I can't install software, how
>can I reinstall XP over itself without crashing my
>computer.. I don't want to lose my files. Can someone
>tell me step by step on how to reinstall XP over itself
>from startup? (I can't do so from the disk while on my
>desktop, I get the installation errors).
>
>thank you
>
>.
>