A single pass of an erase tool is more than sufficient to make the drive unrecoverable when dealing with modern hardware. All this "35 pass" stuff is completely unnecessary and takes a huge amount of time to run. If you really want to know how good a single pass is, pick up the phone to the most expensive data-recovery firm you can find (Vogon are very good and also very expensive), tell them you've just run a DBAN single-pass wipe and see if they'll quote you for recovery.... not a chance in hell.