Nah, no need for Gutman 35. I've tested it myself before I set up FDE. Did a single random write across the whole disk, then used a program to scan for files and found nothing. Not a single file was recovered. NSA might have technology not available to us, but NSA won't be analyzing the hard drive of a low or mid-level drug dealer. They're worried about terrorists and spies. The important thing is you have to write across the whole disk while the host OS is offline (like from a boot disk), filling the empty space is not enough.