If you do use a wipe program, make multiple passes. Just one pass writing ones/zeros won't do the job completely.
I'm surprised at how many people want to know how to completely erase their hard drives. I'm not ashamed of anything I have on my hard drive - even including the slash stories. I do keep a file with passwords to various sites, but they're all innocuous sites anyway. I don't keep my online banking passwords on, and those are the only "important" ones. So what would I care if someone looked at my hard drive? They shouldn't be nosey in the first place.
Back on-topic, we had a teacher at my school who was completely clueless. He "knew people" in the education department, so he got them to assign him to our school in the middle of the term
as a head of department. The principal, naturally, was upset that this was done, so she made life extremely difficult for him (unfair of her, but who has himself assigned to a school as an HOD in the middle of a term?!!).
Anyway, the rest of us felt sorry for him and tried to be supportive - until we found out that he had made up
the marks he gave the children. And he didn't even do it properly - he gave bright children very low marks, weak children high marks, etc., which set off the principal's hinky-metre. She then (to make it look fair) instituted a policy of checking everyone's marks against the work in the books. Even those of us who'd been there for decades and who are scrupulously honest.
Principal tried to get rid of him through channels, but because he knew people, nothing happened. So she gave him the minimum work and distributed his classes among teachers who had a clue. Eventually he got the hint and left - to be the vice-principal of another school. Once again, not due to competence, but simply because he knew people. I pity the staff of the school he went to. Imagine having to carry someone who gets paid much more, but does nothing. To this day when the end of term comes and we have to come and explain "where we got our marks from", we curse this guy in our minds (and sometimes out loud to each other).