Well, the 2 Seagate drives I bought didn’t work. 
I went back the next day and returned 1 and exchanged the other for a SATA version to put in my PC.
So I’ve also asked LaCie about the hardware, and what options I do have according to the spec’s of the components involved.
Posted: 4 March 2008 @ 00:00
I bought a 600Gb Lacie Bigger Disk Extreme Triple Interface a few years ago. It’s started clicking. I can read data off it to back it up, but if I try and use a file on the drive (eg playback a movie file) it doesn’t work. I realise that the drive is outside of warranty, but I do like the case (mainly cos of the 2x FW800 connections on it). I am wanting to find out if it is possible to go and purchase 2x IDE HDD’s and replace the ones in the case, so I can keep using it.
If I can do this, are there any limitations as to what I can do? eg, do I have to replace the drives with exactly the same type of drive (2x 300Gb Maxtor HDD’s), or can I use any 2x HDD’s? Are there any limitations of the Bridge Chipset that I need to know about before I purchase some replacement drives.
Thanks and Best Regards,
Griffmiester
to which I received the reply…
Posted: 5 March 2008 @ 00:00
Hi Griffmiester,
I’m sorry the drive is giving you trouble. You can replace the disks, but the maximum that particular bridge ever had on it was 1TB total (so, two 500 GB IDE disks.) Maxtor would be best for that bridge, but WD should also work. I don’t suggest using Seagate or Hitachi (they’re not bad at all, but they have had a few problems with our Oxford chipset RAID controllers in recent models. If you purchase drives that does have the problem, you would have to return them, which can be frustrating.)
Once you install the new drives, you should just need to format the drive.It’s best to do the “Zero out data” format in Disk Utility to ensure the bridge has full read/write access to the disk.
Thanks,
Patrick
So happily there is still something that I can do about using this external drive. 
Further info to come as I install new disks into the case.