It depends if the person intends to keep the computer or sell/donate it. I have always recommended BitEraser or East-Tec Eraser. BitEraser is great since it provides a Digitally Signed Certificate in the event you consult with companies or people who need proof the data was destroyed.
Of...
Happy 2024 and hope you found a good alternative since originally posting your question concerning encryption issues with TrueCrypt. Since the software provider shut down several years ago. SecurStar, claimed intellectual property theft.
Nonetheless, I would recommend BestCrypt. for either...