failing hard drive

[zapout]

I recently replaced my old HDD (Seagate 80GB 7200 RPM IDE)with new one Seagate 500GB 7200 RPM SATA (ST3500418AS)
I use the speed fan S.M.A.R.T. to check my HDD status it shows fitness & performance of my HDD above 92-93%

but now for past 4 days its fitness keep reducing and now it's at 29%
though the hdd is working fine
and there is no noticeable difference in the performance
(this problem first showed up after a power-out)
http://docs.google.com/Doc?docid=0AVviGJadSNBfZGhmcnBxYnhfMmhrZGRxYmhy&hl=en

but the seatool test results says my hdd is fine

the power supply have no sata power connector
the hard drive is connected with a "molex to sata power" connector(it's safe to use this in long term???)

why this data is changing so rapidly???
is my hdd is failing???

please help!!

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[Quantos]

I would trust SeaTool more than SpeedFan given that it's the correct tool.