I was in a similar situation, but I figured it out. If Disk Utility recognizes it, then go into disk utility and select the lacie hard drive itself (not any volumes/partitions) in the column on the left. Then click the erase tab in the menu on the right. Then, give your hard drive a name, select Mac OS X Extended (Journaled) as the format and then - this is key - select the button that says "options". Select "ZERO ALL DATA" and then click ok. Then click erase on the main screen and you're all set.
By the way - this will take a very long time to complete. My 200GB hard drive took almost six hours to complete. It's well worth it though.
Good Luck,
JOD8FY
P.S. - This will mount it, format it, erase it and give it an image on your desktop.