It is a Western Digital WD2500KS which has the SATA power and data connectors on the left (viewed on the end as if installed), to the right if that is a blank hole, then a block of 8 pins, then what looks like a Molex socket (4 pins with chamfers at the upper corners.
Does that sound right?
Any idea what the 3.3VDC supply is for?
Many thanks for all your responses I shall try to ensure I`m doing everything correctly - these drives are a bit pricey to me!! I shall also look on Google for any further information I can get.