Unless you have corp./gov't/medical/financial secrets/etc., on your HD, then a "write zeros" tool should be likely "good enough". But if the FBI/CIA/MI5/Mossad are all after you, you should physically destroy the drive (shred first, then melt down completely) instead of wipe it.
Your standard DOS "format" program doesn't actually really wipe anything, and is easily recovered from.
Btw, IBM/Hitachi's DFT tool, has an option for "Erase Disk" that does a "Security Erase Prepare" operation on your HD, which can "write zeros" to even some of the internal sectors, it seems. DBAN or Heidi should work just fine though.