there is a distinct possibility writing to the NTFS file system trashes it, the filesystem, not the disk physicaly.
NTFS can be read just fine but the write has been less than 100%, mainly due to Microsoft doing weird things to the file system. in XP and Vista it is even common that it self-destructs.

if it was me I would back up what I can (using knoppix and DVD burner) and reinstall, sadly it is likely the fastest route to a working system.
you DO have backups of things like mail, important documments and images/films, bookmarks...?
also you have al the needed disks for instalation, like drivers, antivirus, installation codes for different programs...
i certainly hope you do, if not you have a HARD lesson ahead.

also you have NO network access during installations, it is more acceptable AFTER you have anti virus and firewall in place and updated, if you allow network access before that it is a good way to get misc malware from start.