I decided to give the RAID x64 drivers on the Asus P5Q-E page a go and lo and behold those drivers were accepted by Vista as newer than the current drivers. I tried the eSATA connection again but still nothing. Nothing in the Device Manager or Drive Management windows.

Incidentally I think I can see the external HDD in the BIOS when it is connected by USB2.

Is there any where to see if the eSATA port is actually 'active' on the PC? I want to be sure that it is 'on' and not off which could explain why nothing is happening?