As I previously explained...if the system has SP3, it will do you no good to try to do a repair install with a disk that reflects SP2. The net result will likely be damaged Windows files or a reversion to SP2, IMO.
If the system is not infected and you have no hardware/partition/file structure problems...a repair install should be effective.
One of the problems with any error involving a stated ntfs.sys file problem...is that it can truly be a file problem...a partition problem...a file system problem...or a hard drive problem.
Ntfs.sys missing or corrupt error message - http://support.microsoft.com/kb/555531
A problem occurred within NTFS.SYS, the driver file that allows the system to read and write to NTFS file system drives. There may be a physical problem with the disk, or an Interrupt Request Packet (IRP) may be corrupted. Other common causes include heavy hard drive fragmentation, heavy file I/O, problems with some types of drive-mirroring software, or some antivirus software."