If you write zeros over every bit on a HDD, there is absolutely never left to recover.
As for your second point, I couldn't agree more. This is supposed to be a holiday weekend. Let's go cook something.
First point, I reiterate, do it several times on the whole drive, at least if you don't want the forensics guys to get it.
Second point, thanks, I did. Herbed lamb chops, compound butter, LO roasted potatoes and corn. Quick and delicious! Enjoy the weekend, jet!