DeepC,
It sounds like the power cuts damaged the OS. I would first try to boot into Safe Mode. If that does not work, I would try:
Boot from the WinXP CD, then go into Recovery Console. Type from the C Prompt:
chkdsk drive /p /r
/p : Does an exhaustive check of the drive and corrects any errors.
/r : Locates bad sectors and recovers readable information.
If that does not work, you can always do a repair with the WinXP CD.
Take Care,
Richard