Recently, my Lacie Big Disk (500GB) died on me. It just stopped appearing as a drive on my PC and I tried it on other machines without success. Looking at some of the forum posts it appeared as if it was going to be one of two problems. Either one (or both) of the drives had failed or the internal controller had failed.
Hoping that it was the controller I decided to get myself another one (eBay to the rescue). Taking both of them apart I swapped the drives from the bust one into the bought one, plugged it in and voila, it worked! So, I copied off all the stuff I wanted to keep then took it apart again.
Now I had four 250GB drives sitting and I can only put two back into the Lacie enclosure. That wouldn't do at all. I acquired myself a 3Ware RAID card (eBay again), albeit an older model as it had to support IDE drives not SATA. On arrival, off came the PC cover and in went the card and the four drives. I fired up the machine and opted for a RAID5 configuration giving me 750GB-ish, left it to format the drives and build the array for a few hours.
Once in Windows I installed the drivers downloaded from the 3Ware support site. I had to force Vista to allow the unsigned drivers but other than that all went smoothly, and now I have 700GB+ fault tolerant drive in my PC. So if you've got an external hard drive, Lacie or otherwise, that's broke and there's a chance it's not the disk itself then there just might be some of getting your data back and re-using the disk.