If I may be blunt, "marcucco" is so completely, totally wrong that I don't even know where to start. Colleen and I are correct.

I say this as an Apple Developer since 1983, and an Apple Product Professional since 2002. I've worked in a fast-paced retail sales and support environment since 2002. I've performed password resets and HD maintenance hundreds of times with the procedure Colleen describes, which obviously directly refutes the evidently not-as-experienced or knowledgeable claims made by other posters here. End of story.

Bottom line: Find or borrow a copy of Mac OS 10.4, a.k.a.Tiger, on CD (or DVD if your machine can read DVDs), boot from it, and invoke the "Password Reset" utility. This question is resolved.